Get Air conditioning system Working with air conditioner service station Guide for Volkswagen Sharan VAN Second Generation (2010-2023)

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

2

Working with air conditioner service

station

⇒ “2.1 Working with air conditioner service station”, page 129

⇒ “2.2 Connecting air conditioner service station to refrigeran^lk

circuit”, page 131

⇒ “2.3 Performing gas analysis of refrigerant”, page 134

⇒ “2.4 Emptying refrigerancircuit”, page 137

⇒ “2.5 Evacuating refrigerancircuit”, page 140

⇒ “2.6 Charging refrigerancircuit”, page 146

⇒ “2.7 Bringing air conditioning system into service after charg‐

ing”, page 149

⇒ “2.8 Switching off air conditioner service station and separating

from refrigerancircuit”, page 151

⇒ “2.9 Charging refrigeranin reservoir”, page 153

⇒ “2.10 Emptying air conditioner service station”, page 154

⇒ “2.11 Cleaning electrical air conditioning compressor”,

page 155

⇒ “2.12 Cleaning refrigerancircuit”, page 157

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder for

analysis, processing or disposal”, page 161

⇒ “2.14 Checking pressures”, page 170

2.1

Working with air conditioner service sta‐

tion

Note

♦ Should there be any reason to believe thachemical substan‐

ces (leak stop additives) have been used to seal leaks in the

refrigerancircuifrom which refrigeranis to be extracted, do

noconnecthe air conditioner service station to this refriger‐

ancircuiand do noextracthe refrigerant.

♦ Chemical substances used to seal leaks form deposits in the

refrigerancircuit. These can impair the function of the air con‐

ditioning system and cause the air conditioning system (and

your air conditioner service station ) to fail.

♦ Bring the customer's attention to the presence of substances

in the air conditioning system thaare noapproved by Volks‐

wagen/Audi, which preventhe air conditioning system from

being flushed and repaired.

♦ Volkswagen/Audi does noauthorise the use of chemical sub‐

stances (leak stop additives) for purposes of sealing leaks in

refrigerancircuits. There are currently no long-term tests, ef‐

fectiveness or material-compatibility tests. As such, there is no

way of ruling oudamage or malfunctions in an air conditioning

system or air conditioner service station .

♦ The leak stop additives currently available on the markehave

differenphysical and chemical properties. These could impair

the function of the air conditioning system and air conditioner

service station with lasting effecor even cause a total failure.

VW/Volkswagen/Audi does noendorse the use of chemical

substances (leak inhibitor additives) for purposes of sealing

leaks in refrigerancircuits.

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♦ These chemical substances (leak stop additives) reacmostly

with the ambienair or the humidity to stop leaks in the refrig‐

erancircuit. They cause deposits to build up in the refrigeran

circui(and your air conditioner service station ), cause valves

to malfunction and defects in other components with which

they come into contact. These deposits cannobe completely

removed from the components (noeven by flushing).

♦ There are often no external signs to suggesthachemical

substances (leak stop additives) have been used to seal leaks

in a refrigerancircuit. Often, the stickers thaare meanto be

used to mark such systems are missing. Therefore, exercise

caution on vehicles for which you have no service or repair

record.

♦ Containers or tanks with integrated filters are offered as ac‐

cessories on the open markethaare designed to separate

these chemical substances (leak stop additives for sealing

leaks). Since Volkswagen/Audi is unaware of the composition

and the physical and chemical properties of these substances,

no statemencan be made athis poinas to the effectiveness

lk

and the filtering capability of these filters.

If repair work needs to be carried ouon the refrigerancircuiof

the air conditioning system on a vehicle whose refrigerancircui

has been filled with chemical substances (leak stop additives) to

seal leaking components (or there is good reason to believe tha

this has been the case), bring the client's (the vehicle owner's)

attention to the following situation:

♦ The refrigeranof the air conditioning system cannobe ex‐

tracted owing to the substances (leak stop additives) thai

contains, which can damage your air conditioner service sta‐

tion . To extracthe refrigerant, ican be filled in a recycling

cylinder in the way described for contaminated refrigeran

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder

for analysis, processing or disposal”, page 161 . Should this

nobe possible, imay be necessary e.g. for a company to be

entrusted with extraction of the contaminated refrigeranusing

a suitable device. This should then be processed (or disposed

of) e.g. by a local disposal company well versed in the proce‐

dures relating to the disposal of refrigerants.

♦ For proper repair of the air conditioning system, iis necessary

to renew all components of the refrigerancircuithahave

come into contacwith the leak stop additive. The leak stop

additive could already have damaged some components of

the refrigerancircui(e.g. the air conditioner compressor reg‐

ulating valve - N280- ) or subsequently cause damage when

the system is broughback into operation and, after a shor

time, failure of said components. Furthermore, deposits of leak

stop additive in the components of the refrigerancircuimay

work loose aa later stage, leading to renewed failure of the

air conditioning system (completely cleaning these compo‐

nents using workshop equipmenis currently nopossible).

♦ Contaminated refrigerancan render the whole filling in your

air conditioner service station unusable.

♦ Before extracting with a suitable tester, check the composition

of the refrigeranin the refrigerancircui

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

♦ Extract contaminated refrigeraninto a recycling cylinder and

send this in to your gas supplier for analysis, processing or

disposal

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

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Note

♦ Contaminated refrigerancan change the way in which the air

conditioning system works and / or permanently damage com‐

ponents of the refrigerancircuit.

♦ Mixtures of differenrefrigerants (e.g. R1234yf refrigeranwith

an unknown quantity of R134a refrigerant) may nobe filled in

a vehicle thahas been given type approval for R1234yf re‐

frigerant.

Importaninstructions for working with air conditioner service sta‐

tion

To operate the air conditioner service station ( air conditioner

service station currently available ⇒ Workshop equipmenand

special tools catalogue ), the following musbe observed:

lk

♦ The fitted filter and dryer musbe renewed athe lateswhen

the operational time specified in the related operating instruc‐

tions has been reached.

♦ If an air conditioner service station is also used to clean (flush)

the refrigerancircuit, the dryer and filter installed in the system

musbe replaced ashorter intervals ⇒ page 124 .

♦ Only refrigeranoils thaare approved for the vehicle-specific

refrigerancircuimay be filled in the reservoir (pour the re‐

frigeranoil directly into the refrigerancircuiif necessary) ⇒

Electronic parts catalogue .

♦ Depending on the version of air conditioner service station and

the measures to be performed, there is a minimum volume of

refrigerant, refrigeranoil and UV leak detection additive tha

musbe in the respective supply reservoirs of the air condi‐

tioner service station ⇒ Operating instructions air conditioner

service station

In the evenof any doubregarding the composition of the refrig‐

eranextracted from the refrigerancircuit, the extracted refriger‐

anmusnobe re-used even after ihas been cleaned in the air

conditioner service station

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

♦ If the wrong refrigeranhas been accidentally poured in the air

conditioner service station , imusbe emptied

⇒ “2.4 Emptying refrigerancircuit”, page 137 and

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 . The system may also need to be cleaned,

including renewal of the filters, dryers and refrigeranoil.

♦ Contaminated refrigerant, e.g. in Germany, can be returned to

the supplier in so-called recycling cylinders for analysis, pro‐

cessing or environmentally-compatible disposal (in other

countries, differenor additional regulations may apply)

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

2.2

Connecting air conditioner service sta‐

tion to refrigerancircui

Connecting

•

Depending on the type of equipmenchosen, there may be

variations in the required procedure; therefore always follow

the user's manual for the equipmenbeing used.

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Note

The procedure described in the instruction manual for your air

conditioning service station is to be followed ⇒ Operating instruc‐

tions air conditioner service station .

The charging hoses musonly be connected according to the fol‐

lowing work procedure to prevenair or moisture from entering

the refrigerancircuit:

– On vehicles with high-voltage system, switch off “stationary air

conditioning” function (deactivate)⇒ Owner's Manual and ⇒

Operating instructions of infotainmen/ MMI .

– Switch off ignition.

– Connect the air conditioner service station to the power sup‐

ply.

– Switch on the air conditioner service station and bring iinto

operation as described in the instructions ⇒ Operating in‐

structions air conditioner service station .

lk

– Unscrew the sealing caps from the service connections (see

vehicle-specific refrigerancircuit) ⇒ Heating, air conditioning;

Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop

manual).

– Evacuate the charge hoses if necessary.

– Check service connections of refrigerancircuifor contami‐

nation or corrosion, clean if necessary.

Note

Diror a rough surface on the service connections caused by cor‐

rosion can cause damage to the seals and thereby premature

failure of the quick-release couplings.

– Fit quick-release couplings to the service connections of the

refrigerancircuit.

NOTICE

Risk of damage to the air conditioner compressor or air condi‐

tioner service station.

Opening the valves with the air conditioning system switched

on can cause a shorcircuibetween the high pressure and low

pressure side.

– Never open valves on the high pressure or low pressure side

with the air conditioning system switched on.

– Turn the handwheel of the quick-release coupling adapter on

the low pressure side no further than necessary to completely

open the service connection (observe pressure gauge; do no

over-tighten valve).

– Perform a gas analysis using the air conditioner service station

(only necessary if refrigeranneeds to be extracted or pres‐

sures in the refrigerancircuineed to be checked)

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

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Note

Connecthe gas analysis device or air conditioner service station

to the refrigerancircuias instructed to do so, and bring iinto

operation ⇒ Operating instructions of gas analysis device ,

⇒ page 131 and / or ⇒ Operating instructions air conditioner

service station .

lk

If during the gas analysis iis found thathe refrigeranin the cir‐

cuimeets the specifications:

– Turn the handwheel of the quick-release coupling adapter on

the high pressure side no further than necessary to completely

open the service connection (observe pressure gauge; do no

over-tighten valve).

– Perform the measures as required on the refrigerancircui

using the air conditioner service station .

Note

♦ If, during the gas analysis, iis found thathe R1234y refrig‐

eranis contaminated, extracthe refrigeranfrom the refrig‐

erancircuiand send iback e.g. to your gas supplier for

processing (or disposal)

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder

for analysis, processing or disposal”, page 161 ,

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 and

⇒ “6.1 Basics of air conditioning technology”, page 16 .

♦ Should there be no means of doing this, extracthe contami‐

nated refrigeranimmediately from the refrigerancircuiof the

vehicle and collecin a recycling cylinder. Unscrew (close) the

handwheel of the quick release coupling adapter on the low

pressure side, switch off the air conditioner service station

(and isolate from the power supply if necessary). Then sepa‐

rate the quick release coupling adapter on the low pressure

side from the vehicle. The quick release coupling adapter on

the low pressure side musthen be separated - e.g. with a

suction hose from the workshop extraction uni- from the

charge hose for the air conditioner service station and the

contaminated refrigeranallowed to flow ouof the charge

hose into the extraction hose of the workshop extraction unit.

To restore operational readiness of the air conditioner service

station , reinstall the quick release coupling adapter on the low

pressure side on the charge hose for the air conditioner serv‐

ice station and evacuate using the air conditioner service

station as instructed to do so in the relevanoperating instruc‐

tions ⇒ Operating instructions air conditioner service station .

– Perform the measures as required using the air conditioner

service station .

♦ ⇒ “2.3 Performing gas analysis of refrigerant”, page 134

♦ ⇒ “2.4 Emptying refrigerancircuit”, page 137 .

♦ ⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

♦ ⇒ “2.6 Charging refrigerancircuit”, page 146 .

♦ ⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151

♦ ⇒ “2.9 Charging refrigeranin reservoir”, page 153 .

♦ ⇒ “2.10 Emptying air conditioner service station”, page 154 .

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♦ ⇒ “2.14 Checking pressures”, page 170

2.3

Performing gas analysis of refrigeran

Note

♦ For operation of the air conditioning system, iis importantha

the refrigeranused has a certain degree of purity.

♦ Contamination with other refrigerants or gases can cause

damage and thereby failure of the air conditioning system.

♦ Contaminated refrigeranmusbe returned as gas of unknown

composition e.g. to your gas supplier for processing (or dis‐

posal) in accordance with legislative requirements ⇒ VW /

Audi-ServiceNe.

♦ To prevenliquid components (e.g. droplets of refrigeranoil)

in the extracted refrigerangas from falsifying the resulof the

gas analysis, separators (filters) are installed in the gas anal‐

ysis device thaseparate these droplets of liquid. Renew

separators in accordance with specifications of gas analysis

device or operating instructions of air conditioner service sta‐

tion ⇒ Operating instructions of gas analysis device or ⇒

Operating instructions of air conditioner service station .

All vehicles

– Connect the gas analysis device or air conditioner service sta‐

tion to the refrigerancircuias instructed to do so, and bring

iinto operation ⇒ Operating instructions of gas analysis de‐

vice ,

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 and / or ⇒ Operating instructions air condi‐

tioner service station .

lk

– Perform the gas analysis as per the operating instructions.

Note

♦ A faulty gas analysis is possible from air in the refrigeranho‐

ses or non-observance of the procedure for gas analysis as

detailed in the operating instructions.

♦ Carefully follow the operating instructions of the gas analysis

device / air conditioner service station .

♦ Evacuate refrigeranhoses of the air conditioner service sta‐

tion before connecting the service couplings to the refrigeran

circui/ gas cylinder with R1234yf refrigeranhose (see oper‐

ating instructions of gas analysis device / air conditioner serv‐

ice station

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

The gas analysis may provide the following results:

♦ The R1234yf refrigerancomplies with the specifications, the

planned measures may be performed with the air conditioner

service station .

♦ A fauloccurred during the gas analysis. The faulis to be in‐

vestigated and rectified after which the gas analysis musbe

repeated.

♦ The analysed R1234yf refrigerandoes nocomply with the

specifications, the analysed refrigeranmusbe extracted as

refrigeranof unknown composition and returned e.g. to your

gas supplier for processing (or disposal)

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lk

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25

Note

♦ Should the analysis of the refrigeran- to be extracted e.g. from

the refrigerancircuiof a vehicle - indicate thaiis contami‐

nated: you can also perform a gas analysis on the refrigeran

e.g. of another cylinder from your gas supplier if you wish to

verify the analysis result.

♦ Since R1234yf refrigeranis so pure, even small amounts of

ambienair in the charge hoses of the air conditioner service

station can falsify the results. For this reason, mosair condi‐

tioner service stations have a feature via which the gas anal‐

ysis is repeated up to 2 times before a noOK resulis

displayed ⇒ Operating manual for air conditioner service sta‐

tion .

♦ You can perform a simple function check on your gas analysis

device e.g. using ambienair (unscrew the service coupling

from the refrigeranhose with which the gas analysis is per‐

formed and analyse the gas with the refrigeranhose open).

The resulof this tesshould then indicate thathe analysed

gas is noOK.

♦ The method of gas analysis employed here was developed for

motor vehicle workshops. Iprovides no details abouthe pre‐

cise composition of the refrigerant. This gas analysis can

therefore only show how high the percentage of R1234yf re‐

frigeranis in the refrigerananalysed. If the percentage of

R1234yf is below 95%, the refrigerandoes nocomply with

the specifications and can cause damage to the components

of the refrigerancircuit. A gas analysis thaalso provides de‐

tails abouthe precise composition of the analysed refrigeran

is currently noavailable for workshops. Gas analyses with

which the precise composition of gases can be investigated

require complicated equipmenand procedures and can usu‐

ally only be performed with dedicated testing facilities.

Should contaminated refrigeranbe found during the gas analy‐

sis, notify the customer before continuing work and bring the

customer's attention to the following:

There is contaminated refrigeranor refrigeranof unknown com‐

position in the refrigerancircuiof his vehicle thadoes no

comply with the vehicle manufacturer's specifications. This re‐

frigerant:

♦ must be returned e.g. to the gas supplier as refrigeranof un‐

known composition for analysis, processing (or disposal)

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

♦ can be the cause of a malfunction or may already have caused

damage thamakes the inevitability of malfunctions in the near

future probable.

♦ Depending on its composition, the use of contaminated refrig‐

erancould lead to the operating permiof the vehicle being

withdrawn.

♦ If, as a resulof contaminated refrigerant, internal damage to

the refrigerancircuihas been caused (e.g. decomposition

products of the contaminated refrigeranhave affected the

components of the refrigerancircui

⇒ “1.5 Renewing components”, page 79 ), the refrigerancir‐

cuican only be restored to full functionality once all compo‐

nents thacame into contacwith the contaminated refrigeran

have been renewed. The internal condition of the refrigeran

circuican be appraised e.g. by visually inspecting certain

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components of the refrigerancircui(e.g. the condition of the

internal surfaces of removed refrigeranlines and refrigeran

hoses, the internal surface of the refrigeranreservoir and the

condition of the removed dryer cartridge).

♦ If internal damage has been caused to the refrigerancircui

through contaminated refrigeran(e.g. failure of the air condi‐

tioner compressor has ensued owing to damaged control

elements or overheating, refrigeranoil has a stronger colour

than usual buthe parts containing refrigeranhave nobeen

affected ⇒ “1.5 Renewing components”, page 79 ), the refrig‐

erancircuican be charged again once ihas been flushed

(renew air conditioner compressor, dryer and expansion

valve). However, since there is no way of anticipating the long-

term effecof the contaminated refrigeranon the refrigeran

oil and the components of the refrigerancircuit, no guarantee

can be given in this case thathe components of the refrigeran

circuiwill function correctly in future.

♦ If the contaminated refrigeranhas nocaused internal dam‐

age to the refrigerancircui(e.g. the refrigeranoil does no

have a stronger colour than usual, the components of the re‐

frigerancircuihave nobeen affected), the refrigerancircui

can be charged again once the dryer has been renewed and

the refrigerancircuihas been evacuated for an extended pe‐

riod (aleas1 hour). However, since there is no way of

lk

anticipating the long-term effecof the contaminated refriger‐

anon the refrigeranoil and the components of the refrigeran

circuit, no guarantee can be given in this case thathe com‐

ponents of the refrigerancircuiwill function correctly in future

⇒ “1.5 Renewing components”, page 79 .

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Note

♦ If there is a complainthacan be attributed to the contamina‐

ted refrigeran(e.g. leaking seals or hoses, damage to the air

conditioner compressor, contaminated refrigeranoil), the re‐

frigerancircuimusbe flushed and then all components tha

were damaged by the contaminated refrigeran(seals, hoses,

reservoir or dryer cartridge, expansion valve and air condi‐

tioner compressor) musbe renewed. If iis found thathe

contaminated refrigeranhas affected other components as

well (e.g. the internal surfaces of the refrigeranpipes and re‐

frigeranhoses, damaged seals), the complete refrigerancir‐

cuimusbe renewed. The refrigerancircuimusthen be

recharged with clean refrigerant. Then check the function of

the air conditioning system. For the customer and to safeguard

yourself, make a note thathe refrigerancircuiwas charged

with contaminated refrigerant.

♦ If there is a complainthacan be attributed to the contamina‐

lk

ted refrigeran(e.g. loss or lack of cooling output) and no other

complaints can be found in the refrigerancircuit, or if the re‐

frigeranhas to be extracted because work in the area of the

refrigerancircuiso requires, proceed as follows after evacu‐

ating the system. Remove the dryer and check for contami‐

nation. Since there could also be refrigeranoil on or in the

dryer, check this as well. If the refrigeranoil is contaminated,

dark or viscous or if deposits of dirhave built-up on the dryer,

flush the refrigerancircuiand renew the parts as described

above (damage may already have been caused, which could

soon lead to failure of the air conditioning system). If the re‐

frigeranoil is OK and the dryer is nocontaminated any more

than is usual from normal operation, renew the dryer. Evacu‐

ate the refrigerancircuifor an extended period (aleas1

hour) and then recharge with clean refrigerant. Check the

function of the air conditioning system. For the customer and

to safeguard yourself, make a note thathe refrigerancircui

was charged with contaminated refrigerant.

2.4

Emptying refrigerancircui

•

Depending on the type of equipmenchosen, there may be

changes to the procedure (always follow user's manual for the

equipmenbeing used) ⇒ Operating instructions air condi‐

tioner service station .

•

The refrigerancircuishould be emptied if parts of the refrig‐

erancircuiare to be removed, if iis unclear whether there is

refrigeranin the circuit, if contaminated refrigeranwas de‐

termined during the gas analysis, or if safety precautions so

demand.

•

All of the operating instructions for work involving refrigeran

with the air conditioner service station can be found in the op‐

erating instructions of the air conditioner service station ⇒

Operating instructions air conditioner service station .

Draining

– On vehicles with high-voltage system, switch off “stationary air

conditioning” function (deactivate)⇒ Owner's Manual .

– Switch off ignition.

– Connect the air conditioner service station to the power sup‐

ply.

In addition for vehicles with electrically-actuated valves in the re‐

frigerancircuithaare noopen when de-energised:

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Note

On vehicles with high-voltage system and auxiliary air condition‐

ing system functions (“heapump mode” or “cooling of high-

voltage battery”), valves may be installed in the refrigerancircui

thaare noopen when de-energised. These valves are opened

and closed e.g. via incremental motors and are no longer actu‐

ated when the ignition is switched off. To empty completely, for

correcevacuation and charging of the refrigerancircuit, howev‐

er, no areas may be isolated, which is why these valves musbe

opened before work is carried ou⇒ Heating, air conditioning;

Rep. gr. 87 ; Refrigerancircuit; System overview - refrigeran

circuiand ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode.

– Using ⇒ Vehicle diagnostic tester, open any valves which are

noopen in their resting state.

All vehicles

– Bring the air conditioner service station into operation as in‐

structed in the associated operating manual.

– Unscrew the sealing caps from the service connections of the

refrigerancircui(see vehicle-specific refrigerancircuit) ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerancircuit;

System overview - refrigerancircui.

– Connect air conditioner service station to refrigerancircui

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

– Perform a gas analysis with the air conditioner service station

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

Note

lk

♦ If during the gas analysis iis found thathe R1234y refrigeran

is contaminated, extracthe refrigeranfrom the refrigeran

circuiand send ie.g. back to your gas supplier for analysis,

processing or disposal

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

♦ Refill the refrigeranthais contaminated into a recycling cyl‐

inder and return ie.g. to your gas supplier for analysis, pro‐

cessing or disposal

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

– Evacuate the refrigerancircuiwith the air conditioner service

station as instructed in the associated operating manual.

NOTICE

Risk of damage to air conditioner compressor if refrigerancir‐

cuiis empty.

– Never starthe engine if the refrigerancircuiis empty.

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Note

♦ Sometimes, refrigeranoil is extracted from the refrigerancir‐

cuialong with the refrigeranand there is no way of stopping

this. In order to ensure the lubrication of the air conditioner

compressor, the refrigeranoil quantity should be topped up

with fresh refrigeranoil

⇒ “2.6 Charging refrigerancircuit”, page 146 .

♦ Where vehicles are fitted with an air conditioner compressor

withoua magnetic clutch (with air conditioner compressor

regulating valve - N280- ) the engine should be run with the

refrigerancircuiempty for no longer than is absolutely nec‐

essary, making sure thahigher engine speeds are avoided

(since the air conditioner compressor will always run when the

engine is running).

♦ On vehicles thahave an air c^lo^knditioner compressor withou

magnetic clutch, the engine may only be started with a com‐

pletely assembled refrigerancircuit, ensuring thahigher en‐

gine speeds are avoided.

♦ Depending on the version of air conditioner compressor, a

valve may be installed on the high-pressure side thaprevents

liquefied refrigeranflowing back into the air conditioner com‐

pressor after the air conditioning system is switched off. If an

air conditioner compressor with this valve is installed in a ve‐

hicle with a refrigerancircuiwith expansion valve, icould

take some time before the pressure on the high-pressure side

drops (the expansion valve is cold and the pressure on the

low-pressure side rises quickly after switching off, the expan‐

sion valve closes and refrigeranonly flows slowly on the low-

pressure side). If the air conditioner compressor is switched

on (or the refrigerancircuiis emptied via the low pressure

side), pressure on the low pressure side drops, the expansion

valve opens and refrigerancan flow on the low pressure side.

If iis necessary after emptying to perform work on the vehicle for

which the air conditioner service station is norequired:

– Detach the air conditioner service station from the refrigeran

circuiand switch off

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

– Open the refrigerancircuiaa connection point.

CAUTION

Risk of freezing injury caused by escaping pressurised refrig‐

erant.

There is a risk of injury to the skin and parts of the body due to

freezing.

– Wear protective gloves.

– Wear protective goggles.

– Extract refrigeranand open the refrigerancircuiimmedi‐

ately afterwards.

– If more than 10 minutes have passed since the refrigeran

was extracted, repeathe extraction process before opening

the refrigerancircuit. Pressure could build up in the refrig‐

erancircuifrom continued evaporation.

– Perform the required measures on the refrigerancircuit.

If, after emptying, the refrigerancircuiis to be evacuated and

recharged ⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

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Note

♦ After opening the connecting points in the refrigerancircuit,

the open lines and componenconnections musbe closed (so

thathe ingress of moisture and dirin these components is

prevented).

♦ Sometimes, refrigeranoil is extracted from the refrigerancir‐

cuialong with the refrigeranand there is no way of stopping

this. To ensure lubrication of the air conditioner compressor,

the refrigeranoil quantity should be topped up with fresh oil.

lk

♦ Where vehicles are fitted with an air conditioner compressor

with air conditioner compressor regulating valve - N280- , the

engine should be run with the refrigerancircuiempty for no

longer than is absolutely necessary, making sure thahigher

engine speeds are avoided (since the air conditioner com‐

pressor will always run when the engine is running).

♦ On vehicles thahave an air conditioner compressor with air

conditioner compressor regulating valve - N280- , the engine

may only be started with a completely assembled refrigeran

circuit, ensuring thahigher engine speeds are avoided.

2.5

Evacuating refrigerancircui

•

The procedure described in the operating manual for your air

conditioning service station is to be followed ⇒ Operating

manual for air conditioner service station .

The refrigeranoil volume in the air conditioner service station

has been checked and, if necessary, adjusted ⇒ Operating

instructions of air conditioner service station .

The refrigeranvolume in the air conditioner service station

has been checked and, if necessary, adjusted ⇒ Operating

manual of air conditioner service station .

Before the refrigerancircuiis filled with refrigerant, imusbe

evacuated, i.e. completely emptied of air. In the process, all mois‐

ture is drawn ouof the circuit.

Leaks can be determined when evacuating the refrigerancircui

⇒ “1.4 Investigating leaks”, page 68 .

NOTICE

Risk of damage to air conditioner compressor with negative

pressure in the refrigerancircuit.

– Never starthe engine if there is negative pressure in the

refrigerancircuit.

Evacuating:

•

The refrigerancircuiis completely assembled.

– On vehicles with high-voltage system, switch off stationary air

conditioning function (deactivate) ⇒ Owner's Manual .

– Switch off ignition.

– Connect the air conditioner service station to the power sup‐

ply.

In addition for vehicles with electrically-actuated valves in the re‐

frigerancircuithaare noopen when de-energised:

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lk

♦ On vehicles with high-voltage system and auxiliary air condi‐

tioning system functions (“heapump mode” or “cooling of

high-voltage battery”), valves may be installed in the refriger‐

ancircuithaare noopen when de-energised. These valves

are opened and closed e.g. via incremental motors and are no

longer actuated when the ignition is switched off. To empty

completely, to evacuate correctly and to charge the refrigeran

circuit, however, no areas may be isolated, which is why these

valves musbe opened before work is carried ou⇒ Heating,

air conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-spe‐

cific workshop manual) and ⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode.

♦ Non-return valves in the refrigerancircuihave a certain hold‐

ing pressure in the direction of flow (approx. 0.1 bar or

100 mbar). To ensure thathe refrigerancircuican be evac‐

uated completely (residual pressure below 5 mbar), all of the

electrically actuated valves mustherefore be open.

– Use the vehicle diagnostic tester to open the electrically-ac‐

tuated valves thaare noopen when de-energised ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode.

All vehicles

– Bring the air conditioner service station into operation as de‐

scribed in the instructions ⇒ Operating instructions air condi‐

tioner service station .

– Unscrew the sealing caps from the service connections of the

refrigerancircui(see vehicle-specific refrigerancircuit) ⇒

Heating, air conditioning system; Rep. gr. 87 ; Refrigerancir‐

cui(vehicle-specific workshop manual).

– Check service connections of refrigerancircuifor contami‐

nation or corrosion, clean if necessary.

Note

Diror a rough surface on the service connections caused by cor‐

rosion can cause damage to the seals and thereby premature

failure of the quick-release couplings.

– Connect the air conditioner service station to the refrigeran

circui

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

– Switch on the air conditioner service station , evacuate the re‐

frigerancircuiand perform the vacuum tes(for a period of

e.g. 10 minutes with the vacuum pump on to remove any air,

remains of refrigeranand moisture and 20 minutes for the

vacuum/pressure increase check).

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Note

♦ The vacuum athe end of the evacuating process (running of

vacuum pump of air conditioner service station ) musbe less

than 5 mbar absolute pressure. Should pressure during the

evacuating process in the refrigerancircuinobe less than

5 mbar, this could have various causes. For example, leaks in

the refrigerancircuior in the connection to the air conditioner

service station , the time for the evacuating process is setoo

short, the vacuum pump of the air conditioner_lkservice station

does nogenerate the necessary vacuum or the vacuum sen‐

sor of the air conditioner service station is nocalibrated prop‐

erly ⇒ Operating instructions air conditioner service station .

♦ An absolute pressure of 5 mbar equates to a vacuum of

975 mbar aan ambienpressure e.g. of 980 mbar.

♦ Athe end of the vacuum/pressure increase check, pressure

in the refrigerancircuishould nobe greater than 20 mbar

absolute. Should the pressure in the refrigerancircuibe

greater than 20 mbar during the vacuum/pressure increase

check, the vacuum pump is switched on and the process is

repeated from the beginning ⇒ Operating instructions air con‐

ditioner service station . Should pressure in the refrigeran

circuistill nobe less than 20 mbar even after the process has

been repeated twice, this could have various causes. For ex‐

ample, there could be leaks in the refrigerancircuit, a leak in

the connection from the refrigerancircuito the air conditioner

service station or in the air conditioner service station itself,

the time sefor the evacuating process is too shorand the

time sefor the vacuum/pressure increase check is too long.

♦ If there is reason to suspeca leak in the refrigerancircuit,

switch off the air conditioner service station if necessary and

allow ito stand for as long as possible (e.g. for aleas1 hour

to check the leak-tightness of the refrigerancircuit) ⇒ Oper‐

ating instructions air conditioner service station .

♦ Depending on the version of air conditioner service station ,

the pressure in the refrigerancircuiis displayed directly.

However, there is also a chance thathe currenpressure is

only displayed while the vacuum pump is running ⇒ Operating

instructions air conditioner service station . In the evenof an

air conditioner service station only displaying the ambien

pressure, the display of the pressure in the refrigerancircui

will depend on the ambienpressure during activation (ambi‐

enpressure a980 mbar, a vacuum of 975 mbar equates to

a residual pressure of 5 mbar absolute).

♦ If the refrigerancircuiwas opened, small quantities of mois‐

ture may have entered the refrigerancircuit. In this case, the

refrigerancircuiis to be evacuated for aleas30 minutes

(pressure in the refrigerancircuibefore charging musbe less

than 20 mbar).

♦ If the refrigeranwas extracted (to check the fill volume) and

the refrigerancircuiwas only evacuated so thaicould be

recharged (the refrigerancircuiwas noopened and is leak-

tight), iis sufficiento evacuate the refrigerancircuifor 5

minutes and to seno time or only a shortime (e.g. 1 minute)

for the vacuum/pressure increase check (no air or moisture

entered the refrigerancircuit).

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♦ Depending on the volume of refrigeranoil in the refrigeran

circuit, the age and mileage of the vehicle, the layouof the

refrigerancircuietc., there is a chance with a leak-tighre‐

frigerancircuiof the specified absolute pressure in the re‐

frigerancircuinorising above the prescribed 20 mbar owing

to refrigeranevaporating ouof the refrigeranoil. Should this

be the case, repeathe process again if necessary and / or

adapthe presetimes accordingly.

If the vacuum display does nochange (and the pressure stays

below 20 mbar), the system is leak-tighand can be recharged.

lk

Note

♦ Depending on the version of air conditioner service station ,

the currenpressure in the refrigerancircuiis permanently

displayed or only displayed after switching on e.g. the “Evac‐

uate” function ⇒ Operating instructions air conditioner service

station .

♦ Due to the high degree of evacuation, there is a chance tha

refrigeran- which evaporates from the refrigeranoil - could

elevate the pressure in the refrigerancircuiduring the vac‐

uum tesfrom 20 to 40 mbar (absolute pressure). This is no

indication of a leak in the refrigerancircuit, though depending

on the version of air conditioner service station icould trigger

a fault. If necessary, evacuate the refrigerancircuiagain and

observe the vacuum display for an extended period. Only if the

vacuum remains steady and you are certain thathe refriger‐

ancircuiis leak-tighis ipermissible to charge the system.

– Charge the refrigerancircuiwith air conditioner service sta‐

tion ⇒ “2.6 Charging refrigerancircuit”, page 146 .

If the vacuum does noremain or sufficienpressure cannobe

built-up, the following action is required:

♦ If pressure in the refrigerancircuionly rises slowly after evac‐

uating e.g. owing to refrigeran(or moisture) evaporating from

the refrigeranoil, evacuate the refrigerancircuiagain and

observe the vacuum gauge for an extended period.

– If there is any doubas to whether the refrigerancircuiis ac‐

tually leak-tight, evacuate again and observe the vacuum

gauge for an extended period. Only when a vacuum is main‐

tained can charging commence.

– Only if you are really sure thathe refrigerancircuiis leak-

tighshould the system be charged

⇒ “2.6 Charging refrigerancircuit”, page 146 .

Further action if a leak is detected during evacuation:

♦ If there is a leak so major thaicauses air to escape to such

a degree during evacuation thathe air conditioner service

station is incapable of generating a sufficienvacuum or the

vacuum gauge indicates immediately after switching off the air

conditioner service station thaair has entered the system and

negative pressure is lost.

– Investigate the leak in the refrigerancircuias follows:

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Note

♦ A larger leak in the refrigerancircuican be detected, for ex‐

ample, by pressurising the circuito a maximum of 15 bar using

cleaned and dried compressed air or nitrogen ⇒ page 124 . If

the leak is large enough, the leakage poincan be detected by

sound as the gas escapes.

♦ The compressed air or nitrogen is introduced to the closed,

empty refrigerancircuivia the service connection -B- to which

through a quick-release coupling adapter -A- has been con‐

nected.

lk

♦ Screw the handwheel -C- into the quick-release coupling

adapter -A- until the valve in the service connection -B- is

completely open - do noover tighten the valve.

♦ The quick-release coupling adapter for service connection can

be fitted e.g. with a modified charging hose -A- (for example

with a M12 x 1.5-6G thread in accordance with SAE J639)

depending on the thread of the quick-release coupling adapter

and a suitable adapter -B- to connecto the workshop com‐

pressed air system ⇒ page 259 . To ensure thano moisture,

oil and dirfrom the workshop compressed air system enter

the refrigerancircuiof the air conditioning system, use e.g. a

combination fine filter unifor compressed air systems with an

oil, dirand water separator, which is commonly used in pain

spraying facilities. Install this between the compressed air sys‐

tem and the charge hose -A- ⇒ Electronic parts catalogue .

♦ Using the manifold gauge with pressure reducer for nitrogen

(maximum reduced pressure: 15 bar) -1- you can conneca

full nitrogen gas cylinder -3- via a charge hose -2- (e.g. with

M12 x 1.5-6G thread in accordance with SAE J639) to the

service connection - to which a quick-release coupling adapter

is connected - of a closed, empty refrigerancircui

⇒ page 258 .

– Slowly increase the pressure in the refrigerancircuito a max‐

imum of 15 bar.

CAUTION

Risk of injury from nitrogen escaping under high pressure.

– Use pressure limiter for nitrogen tank.

– Search for the leak by sound, which can be heard as gas es‐

capes from this point.

– Repair the leak.

– Evacuate refrigerancircuiand observe the vacuum gauge

over a period of hours. Only when a vacuum is maintained can

charging commence.

♦ If a leak is presenof a size where no or very little air is drawn

in - with the refrigerancircuievacuated - and the air condi‐

tioner service station can create sufficienvacuum. The vac‐

uum gauge does noincrease or increases very slowly after

switching the air conditioner service station off. This indicates

thathere may be a very small ingress of air and the vacuum

is lost.

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– Charge the circuiwith 100 g of refrigeranand search for the

possible leak using an electronic leak tester

⇒ “1.4.2 Searching for leaks in refrigerancircuits using an

electronic leak detector”, page 69 or add an approved UV

contrassubstance to the refrigeranand search for the pos‐

sible leak in the circuiusing the leak detector system

⇒ “1.4.3 Searching for leaks with UV leak detection system”,

page 71 .

– Evacuate refrigerancircuiif necessary

⇒ “2.4 Emptying refrigerancircuit”, page 137

– Rectify the problem in the refrigerancircui⇒ Heating, air

conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual).

– Evacuate the refrigerancircuiand observe the vacuum

gauge over an extended period. Only when a vacuum is main‐

tained can charging commence

lk

⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

If iis necessary after evacuating to perform work on the vehicle

for which the air conditioner service station is norequired:

– Detach the air conditioner service station from the refrigeran

circuiand switch off

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

NOTICE

Risk of damage to air conditioner compressor with negative

pressure in the refrigerancircuit.

– Never starthe engine if there is negative pressure in the

refrigerancircuit.

– Ensure that, until the refrigerancircuiis charged, the engine

cannobe started.

If after emptying and evacuating the refrigerancircuiis to be

recharged ⇒ “2.6 Charging refrigerancircuit”, page 146 .

2.6

Charging refrigerancircui

Note

♦ The whole amounof refrigerancan be charged either on the

high pressure side or the low pressure side. Charging of the

refrigerancircuiis described as follows for the high pressure

side.

♦ Fill capacities of refrigeranand refrigeranoil ⇒ Heating, air

conditioning; Rep. gr. 00 ; Technical data .

•

The procedure described in the instruction manual for the air

conditioning service station is to be followed ⇒ Operating in‐

structions of air conditioner service station .

Before charging the system with refrigerant, the amounof re‐

frigeranoil musbe adjusted ⇒ Heating, air conditioning; Rep.

gr. 00 ; Technical data .

Ensure when charging the refrigerancircuithathe air con‐

ditioner service station is athe same level as the vehicle

whose refrigerancircuiis to be charged (no greater than 50

cm difference). If the heighdifference is too great, deviations

may occur between the amounof refrigerandisplayed and

the amounactually charged (depending on the version of air

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conditioner service station ). The filling accuracy of the air

conditioner service station may be affected.

•

The refrigerancircuiis completely assembled ⇒ Heating, air

conditioning; Rep. gr. 87 ; Refrigerancircuit; System over‐

view - refrigerancircui.

– On vehicles with high-voltage system, switch off stationary air

conditioning function (deactivate) ⇒ Owner's Manual .

– Switch off ignition.

– Connect the air conditioner service station to the power sup‐

ply.

– Check the volume of refrigerant, the volume of refrigeranoil

and the amounof UV leak detection additive in the air condi‐

tioner service station and replenish as necessary ⇒ Operating

instructions air conditioner service station .

In addition for vehicles with electrically-actuated valves in the re‐

frigerancircuithaare noopen when de-energised:

Note

On vehicles with high-voltage system and auxiliary air condition‐

ing system functions (“heapump mode” or “cooling of high-

voltage battery”), valves may be installed in the refrigerancircui

thaare noopen when de-energised. These valves are opened

and closed e.g. via incremental motors and are no longer actu‐

ated when the ignition is switched off. To empty the refrigeran

circuicompletely or to evacuate and charge icorrectly, however,

no areas musbe isolated. Therefore, these valves musbe

opened before performing these types of work ⇒ Heating, air

conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual) and ⇒ Vehicle diagnostic tester in “Guided

FaulFinding” mode.

– Use the vehicle diagnostic tester to open the electrically-ac‐

tuated valves thaare noopen when de-energised ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode.

All vehicles

– Bring the air conditioner service station into operation as de‐

scribed in the instructions ⇒ Operating instructions air condi‐

tioner service station .

– Unscrew the sealing caps from the service connections of the

refrigerancircui(see vehicle-specific refrigerancircuit) ⇒

Heating, air conditioning system; Rep. gr. 87 ; Refrigerancir‐

cui(vehicle-specific workshop manual).

– Connect quick-release couplings to the service connections of

the refrigerancircui

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

– Evacuate the refrigerancircuiwith the air conditioner service

station ⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

– Adjust the requisite amounof refrigerant, the amounof re‐

frigeranoil to be replenished if necessary and the amounof

UV leak detection additive in the air conditioner service station

⇒ Operating instructions air conditioner service station , ⇒

Heating, air conditioning; Rep. gr. 00 ; Technical data (vehicle-

specific workshop manual).

– Choose the relevansetting on the air conditioner service sta‐

tion for charging on the high pressure side ⇒ Operating

instructions air conditioner service station .

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When charging the refrigerancircuion the low pressure side,

liquefied refrigerancould accumulate in the compression cham‐

ber of the air conditioner compressor.

– Should ibe necessary to charge the refrigerancircuion the

low pressure side, turn the air conditioner compressor 10

times by hand before bringing into operation for the firstime

after charging (if necessary, remove e.g. the drive belto fa‐

cilitate this).

Note

♦ Refrigeranand refrigeranoil are charged in the refrigeran

circuion the high pressure side.

♦ If a vehicle has no service connection on the high pressure

side of the refrigerancircuit, refrigerancan also be charged

via the service connection on the low pressure side. To do this,

lk

however, always observe the setting and the operating in‐

structions of the air conditioner service station .

♦ If on an air conditioner service station the charging device

cannobe adjusted, unscrew (close) the handwheel on the

quick-release coupling adapter on the low pressure side if

necessary.

– Charge the refrigerancircuiwith the requisite amounof re‐

frigerant, the amounof refrigeranoil thaneeds to be replen‐

ished if necessary and the amounof UV leak detection

additive.

– Bring the air conditioning system into operation after charging

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircuit;

Bringing air conditioning system into operation after charging

refrigerancircui(vehicle-specific workshop manual) and

⇒ “2.7 Bringing air conditioning system into service after

charging”, page 149

Bringing air conditioning system with electrical air conditioning

compressor into operation

– Bring the air conditioner compressor into operation via “Basic

setting, compressor run-in” function in guided faulfinding

⇒ Vehicle diagnostic tester.

In addition for vehicles with electrically-actuated valves in the re‐

frigerancircuithaare noopen when de-energised:

– Use the vehicle diagnostic tester to enable (open or close) the

electrically-actuated valves - thaare noopen when de-ener‐

gised - for operation of the air conditioning system via the

respective control uni⇒ Vehicle diagnostic tester in “Guided

FaulFinding” mode.

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Note

On vehicles with high-voltage system and auxiliary air condition‐

ing system functions (“heapump mode” or “cooling of high-

voltage battery”), valves may be installed in the refrigerancircui

thaare noopen when de-energised. These valves are opened

and closed e.g. via incremental motors and are no longer actu‐

ated when the ignition is switched off. To completely empty,

correctly evacuate and charge the refrigerancircuit, however, no

areas may be isolated. Therefore, these valves musbe opened

before these measures are carried out. On completion of the

work, enable actuation of these valves again via the respective

control uni⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigeran

circui(vehicle-specific workshop manual) and ⇒ Vehicle diag‐

nostic tester in “Guided FaulFinding” mode.

All vehicles

If iis necessary to perform a function check after charging the

refrigerancircuit:

lk

– Check the pressures in the refrigerancircui⇒ page 170 .

If iis nonecessary to perform a function check after charging

the refrigerancircuit:

– Detach the air conditioner service station from the refrigeran

circuiand switch off

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

2.7

Bringing air conditioning system into

service after charging

Note

♦ If the mechanical air conditioner compressor was removed,

turn iapprox. 10 times by hand before initial operation (during

installation or after installation e.g. before fitting the belt) so

thano damage is caused from a fluid shock when iis switch‐

ed on the firstime (if there is refrigeranoil in the cylinder of

the air conditioner compressor, this will be forced ouby turn‐

ing) ⇒ Heating, air conditioning; Rep. gr. 87 ; Air conditioner

compressor; Removing and installing air conditioner compres‐

sor .

♦ If the electrical air conditioner compressor was removed, be‐

fore bringing the air conditioning system into operation for the

firstime and after charging, the air conditioner compressor is

to be broughinto operation via the “Basic setting, compressor

run-in” function in guided faulfinding ⇒ Vehicle diagnostic

tester in “Guided FaulFinding” mode - air conditioning system

and battery regulation. This prevents damage to the air con‐

ditioner compressor, e.g. from a fluid shock, during initial

activation (if there is refrigeranoil in the compression cham‐

ber of the air conditioner compressor, this will be forced out).

♦ The mechanical air conditioner compressor is driven by the

engine via a belor a shaft. The electrical air conditioner com‐

pressor is driven by an electric motor mounted directly on the

air conditioner compressor (e.g. on vehicles with hybrid drive)

⇒ Heating, air conditioning; Rep. gr. 87 ; Air conditioner com‐

pressor; Removing and installing air conditioner compressor .

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Bringing air conditioning system with mechanical air conditioning

compressor into operation

– Switch on ignition.

– Set the air conditioning system to the lowesoutpupossible

(e.g. selecoperating mode “A/C OFF”).

– Switch off actuation of the air conditioner compressor (e.g.

selecoperating mode “A/C OFF”).

– Start the engine with the air conditioner compressor switched

off (e.g. operating mode “A/C OFF” selected).

– Wait until idling speed has stabilised:

– Switch air conditioner compressor on and lesystem run for a

leas2 minutes with engine idling.

– If necessary, check the pressures in the refrigerancircuius‐

ing the air conditioner service station ⇒ page 129 .

– Switch off engine.

– Detach the air conditioner service station from the refrigeran

circuiand switch off

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

Bringing air conditioning system with electrical air conditioning

compressor into operation

– Switch on ignition.

– Bring the air conditioner compressor into operation via the

“Basic settings, compressor run-in” function of guided faul

finding ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode - air conditioning system and battery regulation.

In addition for vehicles with electrically-actuated valves in the re‐

frigerancircuithaare noopen when de-energised:

– Use the vehicle diagnostic tester to enable (open or close) the

electrically-actuated valves - thaare noopen when de-ener‐

gised - for operation of the air conditioning system via the

respective control uni⇒ Vehicle diagnostic tester in “Guided

FaulFinding” mode.

Note

On vehicles with high-voltage system and auxiliary air condition‐

ing system functions (“heapump mode” or “cooling of high-

voltage battery”), valves may be installed in the refrigerancircui

thaare noopen when de-energised. These valves are opened

and closed e.g. via incremental motors and are no longer actu‐

ated when the ignition is switched off. To completely empty,

correctly evacuate and charge the refrigerancircuit, however, no

areas may be isolated. Therefore, these valves musbe opened

before these measures are carried out. On completion of the

work, enable actuation of these valves again via the respective

control uni⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigeran

circuit; System overview - refrigerancircuiand ⇒ Vehicle diag‐

nostic tester in “Guided FaulFinding” mode.

All air conditioning systems with electrical air conditioning com‐

pressor

– After the basic setting, check the pressures in the refrigeran

circuiif necessary using the air conditioner service station .

– On vehicles with high-voltage system, switch off “stationary air

conditioning” function (deactivate)⇒ Owner's Manual .

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– Switch off ignition.

– Detach the air conditioner service station from the refrigeran

circuiand switch off

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

lk

Vehicles with electrical air conditioning compressor

•

The engine may only be started when the refrigerancircui

has been fully assembled.

•

On vehicles with battery cooling, hybrid operation is only pos‐

sible with the air conditioning system charged and no faults

stored in connection with the air conditioning system ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air condi‐

tioning system and battery regulation.

•

Firsbring the electrical air conditioner compressor into oper‐

ation after installing the air conditioner compressor and charg‐

ing the refrigerancircuivia the “Compressor run-in” function

in basic settings. Should there be an accumulation of refriger‐

anoil in the compression chamber of the air conditioner

compressor before installation owing to unfavourable storage,

damage could be caused to the air conditioner compressor

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system and battery regulation.

An electrically driven air conditioner compressor may only be

activated when the refrigerancircuiis charged. Running the

air conditioner compressor with the refrigerancircuiempty

could lead to compressor damage ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system and

battery regulation.

– To minimise the number of automatic engine starts when the

vehicle's drive system is active (READY) during tesand

measuremenwork, charge the vehicle batteries e.g. with the

battery charger 60 A - VAS 5904- in battery standby mode ⇒

Electrical system - General information; Rep. gr. 27 ; Charging

battery and ⇒ Electrical system; Rep. gr. 93 ; General warn‐

ings for work on the high-voltage system .

– For tesand measuremenwork tharequires the vehicle's

drive system to be active (READY) or the ignition to be switch‐

ed on, move the selector lever to position “P”, activate the

parking brake and arrange the tools needed so thathey can‐

nocome into contacwith moving components of the engine

and so thathey cannoeven come near to components tha

turn when the engine is running.

2.8

Switching off air conditioner service sta‐

tion and separating from refrigerancir‐

cui

– Finish the requisite work with the air conditioner service sta‐

tion .

– Switch off ignition.

– Unscrew (close) the handwheels of both service couplings.

2. Working with air conditioner service station

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CAUTION

Risk of freezing injury caused by escaping pressurised refrig‐

erant.

There is a risk of injury to the skin and parts of the body due to

freezing.

– Wear protective gloves.

– Wear protective goggles.

– If, when loosening the handwheel of the service coupling,

refrigeranescapes from the refrigeranline for longer than

1 second, screw in the handwheel and renew the defective

valve.

– Extract refrigeranand open the refrigerancircuiimmedi‐

ately afterwards.

– If more than 10 minutes have passed since the refrigeran

was extracted, repeathe extraction process before opening

the refrigerancircuit. Pressure could build up in the refrig‐

erancircuifrom continued evaporation.

lk

Differenversions of service couplings

♦ On one version of service coupling, the space between the

valve in the service connection of the refrigerancircuiand the

valve in the service coupling is vented externally when the

handwheel is unscrewed. On these service couplings, the

valve in the service connection of the vehicle is closed first,

followed by the valve in the service coupling for the charge

hose of air conditioner service station when the handwheel of

the service coupling is unscrewed. As iis unscrewed further,

the pressure still presenbetween the two valves is released

3

via an additional valve (approx. 2 cm of refrigerant). Should

one of these two valves (the valve in the service connection of

the vehicle or the valve in the service coupling for the charge

hose) noclose properly, the whole refrigerancould escape

ouof the refrigerancircuiof the vehicle or the charge hose.

♦ On another version of service coupling, the space between the

valve in the service connection of the refrigerancircuiand the

valve in the service coupling is novented externally when the

handwheel is unscrewed. This version features a valve thais

open when the service coupling is connected, which facilitates

pressure compensation between the space to the valve in the

service connection of the refrigerancircuiand the charge

hose connected to the service coupling. On this version, no

refrigeranescapes when the handwheel of the service cou‐

pling is unscrewed, which is why the refrigeranhas to be

extracted from the charge hoses into the air conditioner serv‐

ice station here before the service couplings are disconnected.

If a large amounof refrigeranis recovered here, for example,

after a pressure tesor after charging the refrigerancircui

(more than approx. 50 g), this is an indication thaa valve in

one of the service connections of the refrigerancircuicould

be leaking and refrigeranis escaping from the refrigerancir‐

cuiof the vehicle (extracrefrigeranand renew the defective

valve)

Before extracting the refrigeranfrom the charge hoses into the

air conditioner service station , unscrew the handwheels of both

service couplings as far as they will go.

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Note

♦ Stored in the air conditioner service station is a function via

which iis switched to a specific operating mode when deac‐

tivated. The whole refrigeranis extracted from the charge

hoses into the air conditioner service station with this function.

♦ If the handwheels of the two service couplings are noun‐

lk

screwed when this function is activated, refrigerancould be

extracted from the vehicle's refrigerancircuit.

– Extract the refrigeranfrom the two charge hoses using the air

conditioner service station as instructed in the relevanoper‐

ating manual ⇒ Operating instructions of air conditioner serv‐

ice station .

Note

♦ If, on an air conditioner service station with a service coupling

thadoes novento the outside, this process takes longer

than approx. 2 minutes or quite a large amounof refrigeran

is extracted, this suggests thathere is a faulin one of the

valves in a service connection.

♦ If, on an air conditioner service station with a service coupling

thadoes vento the outside, this process takes longer than

approx. 2 minutes, this suggests thathere is a faulin one of

the valves in a service coupling.

Note

Erroneous extraction from vehicle's refrigerancircuit.

– First unscrew (close) the handwheels of the quick-release

coupling adapters.

– Then extracthe refrigeranfrom the two charge hoses using

the air conditioner service station.

– Switch off the air conditioner service station (and isolate ifrom

the power supply if necessary) ⇒ Operating instructions air

conditioner service station .

– Separate the quick-release couplings from the service con‐

nections of the refrigerancircuit.

– Screw the sealing caps on the service connections (see vehi‐

cle-specific refrigerancircuit) ⇒ Heating, air conditioning;

Rep. gr. 87 ; Refrigerancircuit; System overview - refrigeran

circui.

2.9

Charging refrigeranin reservoir

– Connect the cylinder with fresh R1234yf refrigeranto the

service coupling on the high pressure side of the air condi‐

tioner service station ⇒ Operating instructions air conditioner

service station .

– Perform a gas analysis on the refrigeran(from the cylinder

supplied) with which the system is to be charged using the air

conditioner service station

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

•

The procedure described in the operating manual for your air

conditioning service station is to be followed ⇒ Operating

manual for air conditioner service station .

2. Working with air conditioner service station

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CAUTION

Risk of explosion from overfilling refrigeranreservoirs.

Refrigerancan expand and cause reservoirs to bursif they are

overfilled.

– Use a refrigerantank with safety valve.

– Never exceed the permissible fill level of the refrigerantank.

Note

Depending on the version of air conditioner service station and

the measures to be performed, there is a minimum volume of re‐

frigerant, refrigeranoil and UV leak detection additive thamus

be in the respective supply tank of the air conditioner service sta‐

tion ⇒ Operating instructions air conditioner service station

2.10

Emptying air conditioner service station

Note

♦ If iis necessary to discharge the air conditioner service station

lk

(e.g. because contaminated refrigeranwas extracted), all fil‐

ters and dryers musbe renewed (do noremove filter and

dryer from the air-tightransporpackage until immediately

before installation to keep absorption of moisture as low as

possible).

♦ If iis necessary to empty the air conditioner service station

(e.g. because certain measures have to be performed on the

air conditioner service station and the refrigeranthahas been

or is to be extracted from the air conditioner service station

complies with the specifications (is nocontaminated), ican

be filled into a recycling cylinder, if necessary, and then reused

⇒ Operating instructions air conditioner service station .

♦ Refrigerancylinders thahave been charged with contamina‐

ted or used refrigeranare referred to as “recycling cylinders”

or “R cylinders”.

♦ Always evacuate recycling cylinders before the firsfilling (re‐

frigerancylinders containing air musnobe filled with refrig‐

erant).

♦ Differentypes of refrigeranmusnobe mixed toher (mix‐

tures of refrigerancannobe recycled, bumusbe disposed

of instead). If the composition of the contents in the cylinder is

noclear, the gas processing / gas disposal company musbe

informed of this

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder

for analysis, processing or disposal”, page 161 and

⇒ “6.2.17 Returning contaminated R1234yf refrigeranfor

analysis, processing or disposal”, page 25 .

CAUTION

Risk of explosion from overfilling refrigeranreservoirs.

Refrigerancan expand and cause reservoirs to bursif they are

overfilled.

– Use a refrigerantank with safety valve.

– Never exceed the permissible fill level of the refrigerantank.

There are various ways to empty an air conditioner service sta‐

tion , observe the operating instructions of the air conditioner

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service station ⇒ Operating instructions air conditioner service

station .

– Drain the refrigeranfrom the air conditioner service station to

be emptied into a differenair conditioner service station , ob‐

serving the operating instructions of the air conditioner service

station to do so ⇒ Operating instructions air conditioner serv‐

ice station and

⇒ “2.13 Filling contaminated refrigeranin a recycling cylinder

for analysis, processing or disposal”, page 161 .

2.11

Cleaning electrical air conditioning com‐

pressor

Vehicles with high-voltage system

Observe the additional warnings for working on vehicles with

high-voltage system ⇒ Electrical system; Rep. gr. 93 ; General

warnings for work on the high-voltage system .

If repair work in the vicinity of high-voltage components and ca‐

bles is necessary, carry oua visual check for damage on high-

voltage components and cables, and observe the warnings ⇒

Electrical system; Rep. gr. 93 ; General warnings for work on the

lk

high-voltage system .

If repair work on high-voltage components is necessary, de-en‐

ergise the high-voltage system ⇒ Electrical system; Rep. gr. 93 ;

De-energising high-voltage system , and “observe the general

warnings for work on the high-voltage system” ⇒ Electrical sys‐

tem; Rep. gr. 93 ; General warnings for work on the high-voltage

system .

Flushing air conditioner compressor

Note

♦ On an electrical air conditioning compressor, the refrigeranoil

cannobe poured ou(as there is no oil drain plug), i.e. the

design makes no allowance for the drainage of oil

♦ With an electrical air conditioning compressor, the refrigeran

oil is to be removed in the direction of flow by flushing (flushing

in the opposite direction of flow is nopossible due to the in‐

tegrated valves).

♦ The air conditioner compressor musbe positioned for flushing

so thathe connection for the refrigeranline on the high pres‐

sure side is athe lowespoinpossible.

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1 - Air conditioner service sta‐

tion

❑ With electronics and

flushing program, air

conditioner service sta‐

tion with flushing device

⇒ Electronic parts cata‐

logue .

❑ If an air conditioner

service station withou

flushing program is

used, the sequence has

to be carried ouman‐

ually (evacuate, flush

4 times with aleas2 kg

of refrigeraneach time

and extracrefrigeran

again, evacuate).

lk

2 - Refrigeranhose of air con‐

ditioner service station

❑ From high pressure side

of air conditioner service

station (normally col‐

oured red) for connect‐

ing low pressure side of

air conditioner compres‐

sor to refrigerancircui

(larger diameter)

3 - Adapter to connection for

low pressure side on air condi‐

tioner compressor

❑ Different versions de‐

pending on vehicle

⇒ “1.6.8 Adapters for

setting up flushing cir‐

cuits”, page 105

❑ The item to be used be‐

tween the refrigeran

hose -2- and adapter -3- is adapter - VAS 6338/48- .

❑ From adapter case VW/Audi passenger vehicle se

4 - Refrigeranline

❑ For connection of air conditioner compressor to adapter ⇒ Item 3 (page 156)

5 - Electrical air conditioner compressor

❑ Flush the air conditioner compressor in normal direction of flow (from low pressure inleto high pressure

outlet)

❑ In order to flush as much refrigeranoil ouof the air conditioner compressor as possible, make sure tha

the high pressure outleof the air conditioner compressor is in the lowesposition possible

Note

♦ Depending on the air conditioner

compressor, a new air condition‐

er compressor mighbe filled

with quite a large amounof re‐

frigeranoil (see manufacturer

plate on air conditioner compres‐

sor and

⇒ “5.2 Refrigeranoil capacities”,

page 15 ).

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♦ On a new air conditioner com‐

pressor filled with more than

150 cm³, pour ouas much re‐

frigeranoil as possible before

flushing.

♦ Reason: The oil volume to be

displaced in one work step may

be restricted depending on the

version of air conditioner service

station .

Note

If the clean refrigeranoil is poured

ouof a new air conditioner com‐

lk

pressor into a clean container and

this is subsequently sealed air-tight,

the refrigeranoil can be re-used to

top-up the refrigeranoil volume in

the circuit.

6 - Refrigeranline

❑ For connection of air conditioner compressor to adapter ⇒ Item 7 (page 157)

❑ Use a refrigeranline e.g. with parnumber 7L6 820 721 BF to set-up the flushing circui⇒ Electronic

parts catalogue

7 - Adapter for connection on high pressure side of air conditioner compressor

❑ Different versions depending on vehicle ⇒ “1.6.8 Adapters for setting up flushing circuits”, page 105

❑ From adapter case VW/Audi passenger vehicle se

8 - Charging hose of flushing device for refrigerancircuits

❑ From connection to high pressure side of air conditioner compressor on refrigerancircui(smaller di‐

ameter) to inleof flushing device for refrigerancircuits.

9 - Flushing device for refrigerancircuits

❑ Different versions and differendesign of flushing devices for refrigerancircuits ⇒ Electronic parts cata‐

logue (Tools; Workshop equipment/tools; Air conditioning/heating)

❑ With filter, sighglass, safety valve, heating, refrigerantank, etc. (depending on version).

❑ Depending on the layouof the air conditioner service station and the flushing device for refrigeran

circuits, there may be a service coupling for refrigerancircuits fitted athe outleand in some cases a

the inleof the flushing device. If a service connection with a valve is installed to the outleof the flushing

device, this valve musbe opened completely when the service coupling is connected. If the valve is no

opened completely, irestricts the refrigeranflow.

❑ If there is a connection for a service coupling fitted athe inleof the flushing device, the inlemusbe

adapted to allow for the refrigeranhose coming from the vehicle to be connected directly.

Note

A service coupling and a valve in the

inleof the flushing device restric

the refrigeranflow from the vehicle

into the flushing device.

10 - Refrigeranhose of air conditioner service station

❑ From the low pressure side of the air conditioner service station (normally coloured blue) to the outleof

the flushing device for refrigerancircuits.

2.12

Cleaning refrigerancircui

– Perform preparatory measures for cleaning (flushing with

R1234yf refrigerant)

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⇒ “1.6.2 Preparations for cleaning refrigerancircui(flushing

with R1234yf refrigerant)”, page 94

– Check the refrigeranvolume in the air conditioner service sta‐

tion . There musbe aleas6 kg of R1234yf refrigeran⇒

Operating instructions of air conditioner service station .

– Empty container for used oil of air conditioner service station

⇒ Operating instructions of air conditioner service station .

– Connect the supply hose (high pressure side) of the air con‐

ditioner service station with an adapter to the low pressure line

leading to the air conditioner compressor (line with larger di‐

ameter)

⇒ “1.6.8 Adapters for setting up flushing circuits”, page 105 .

– Connect the return hose (low pressure or suction side) of the

air conditioner service station to the outleof the flushing de‐

vice for refrigerancircuits.

– Connect the inleof the flushing device for refrigerancircuits

with an adapter to the high pressure line leading to the air

lk

conditioner compressor (line with smaller diameter)

⇒ “1.6.8 Adapters for setting up flushing circuits”, page 105 .

♦ Principle circuidiagrams for various flushing circuits

⇒ “1.6 Cleaning refrigerancircuit”, page 92

♦ Adapters for setting up flushing circuits

⇒ “1.6.8 Adapters for setting up flushing circuits”, page 105

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Note

♦ The components are almosalways flushed againsthe direc‐

tion of refrigeranflow when the air conditioning system is in

operation. (Exception: electrically-actuated air conditioner

compressor) ⇒ page 92 .

♦ When flushing, contaminants from the refrigerancircuienter

the flushing device for refrigerancircuits and the air condi‐

tioner service station and are retained in the filters and dryers

installed within. Depending on the contamination, these com‐

ponents musbe renewed ashorter intervals than prescribed

as per the operating instructions of the air conditioner service

station or flushing device for refrigerancircuits ⇒ Operating

lk

instructions of air conditioner service station .

♦ The filter in the flushing device for refrigerancircuits should

be changed (depending on the type and severity of contami‐

nation in the flushed refrigerancircuits) after abou5 to 10

flushing cycles (flushed vehicles). If a heavily contaminated

refrigerancircuiis flushed (the refrigeranoil from the refrig‐

erancircuiis black and viscous or there are large amounts

of swarf in the refrigerancircuit), renew the filter after flushing

this refrigerancircuit. After such heavy contamination of the

refrigerancircuit, iis a good idea to flush the system again

after replacing the filter.

♦ Depending on the type of contamination, deposits (old refrig‐

eranoil and friction dusfrom the air conditioner compressor)

will gather in the sighglass of the rinsing device for refrigeran

circuits. If necessary, clean this sighglass after flushing and

flush the refrigerancircuithrough again to make sure iis

clean (one pass is sufficienin this instance).

♦ Liquid refrigerancannobe routed through the expansion

valve, restrictor and desiccanbag of certain receivers athe

necessary rate. Therefore remove these components and re‐

place them with adapters if applicable ⇒ page 92 and ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerancircuit;

System overview - refrigerancircui(vehicle-specific work‐

shop manual).

♦ Adapters to connecair conditioner service station and to

bridge certain components of the refrigerancircui

⇒ “1.6.8 Adapters for setting up flushing circuits”, page 105 .

Perform flushing (the procedure runs automatically as per the

program in the air conditioner service station ⇒ Operating in‐

structions of air conditioner service station )

– Switch on the air conditioner service station ⇒ Operating in‐

structions of air conditioner service station .

– Select the flushing program on the air conditioner service sta‐

tion ⇒ Operating instructions of air conditioner service station .

– Flush the refrigerancircui(duration approx. 1 to 1.5 hours for

one flushing cycle with 4 cycles) ⇒ Operating instructions of

air conditioner service station .

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Note

♦ Flushing procedure

⇒ “1.6.3 Refrigerancircuicleaning procedure”, page 96 .

♦ Perform flushing as instructed in the operating manual of the

air conditioning service station ⇒ Operating instructions of air

conditioner service station .

♦ Depending on the type of air conditioning service station , the

used oil tank has a capacity of abou125 cm ³of refrigeran

oil. If a system with a greater amounof refrigeranoil has to

be flushed, imay be necessary to empty the used oil tank after

the firsflushing process of a flushing cycle.

♦ Observe the refrigeranflowing back into the air conditioning

service station from the refrigerancircuit. Once the refrigeran

flows clear and completely colourless through the inspection

window of the flushing device for refrigerancircuits in the air

conditioning service station , the refrigerancircuiis cleaned.

♦ When flushing, the whole amounof refrigeranoil from the

refrigerancircuiis washed ou(excepfor a very small

amount, e.g. in the evaporator, buthis is negligible).

♦ Where contamination is particularly high, imay be necessary

to carry outhe flushing process twice (two flushing cycles with

4 flushing processes each).

– At the end of the flushing process, check the inspection win‐

dow or windows of the flushing device for refrigerancircuits.

If dirty, clean as per the instructions of the flushing device for

refrigerancircuits or air conditioner service station and per‐

form the flushing process again ^lt^ko be safe (running through

once over a period of approx. 30 min. is sufficient) ⇒ Operating

instructions air conditioner service station .

– Check the pressure in the refrigerancircuit. There musbe no

overpressure in the refrigerancircui(evacuate twice briefly if

necessary).

– Remove the connections to the air conditioning service station

from the refrigerancircuiof the vehicle (there should be no

overpressure in the refrigerancircuit)

– Renew these vehicle-specific components (restrictor and res‐

ervoir, expansion valve and receiver / dryer cartridge in the

reservoir) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refriger‐

ancircuit; System overview - refrigerancircui(vehicle-spe‐

cific workshop manual) and ⇒ Electronic parts catalogue .

– Depending on the complaint, renew the air conditioner com‐

pressor ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigeran

circuit; System overview - refrigerancircui(vehicle-specific

workshop manual) and ⇒ Electronic parts catalogue or drain

the remaining refrigeranoil from the removed air conditioner

compressor ⇒ “1.5 Renewing components”, page 79 and fill

with the requisite amounof fresh refrigeranoil again ⇒ Heat‐

ing, air conditioning; Rep. gr. 00 ; Technical data (vehicle-

specific workshop manual) and ⇒ Heating, air conditioning;

Rep. gr. 00 ; Technical data; Refrigeranoil .

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Note

♦ Replacemencompressors c_lo_kntain a certain specified quantity

of refrigeranoil. On vehicles with two evaporators, a certain

amounof refrigeranoil may also have to be filled in the circui

if necessary ⇒ Heating, air conditioning; Rep. gr. 00 ; Tech‐

nical data; Refrigeranoil .

♦ If the air conditioner compressor does noneed to be renewed,

replenish the refrigeranoil accordingly up to the prescribed fill

level (empty or flush refrigeranoil and pour the prescribed

volume back into the air conditioner compressor or refrigeran

circuit) ⇒ “1.5 Renewing components”, page 79 and ⇒ Heat‐

ing, air conditioning; Rep. gr. 00 ; Technical data; refrigeran

oil .

– Completely reassemble the refrigerancircuiagain ⇒ Heat‐

ing, air conditioning; Rep. gr. 87 ; Refrigerancircuit; System

overview - refrigerancircui(vehicle-specific workshop man‐

ual).

– Evacuate and charge the refrigerancircuiin accordance with

the specifications

⇒ “2.5 Evacuating refrigerancircuit”, page 140 ,

⇒ “2.6 Charging refrigerancircuit”, page 146 and ⇒ Heating,

air conditioning; Rep. gr. 00 ; Technical data .

– Bring the air conditioning system into operation in the prescri‐

bed manner ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircuit; Bringing air conditioning system into operation

after charging refrigerancircui(vehicle-specific workshop

manual) and

⇒ “2.7 Bringing air conditioning system into service after

charging”, page 149

2.13

Filling contaminated refrigeranin a re‐

cycling cylinder for analysis, processing

or disposal

⇒ “2.13.1 Filling contaminated refrigeranin a recycling cylinder

using technical equipment”, page 161

⇒ “2.13.2 Filling undercooled contaminated refrigeranin a recy‐

cling cylinder”, page 164

2.13.1

Filling contaminated refrigeranin a re‐

cycling cylinder using technical equip‐

men

Note

♦ Some manufacturers may provide accessory devices (extract‐

ing or disposal units) thathey claim to be approved for the

extraction of gases of unknown composition. These devices,

however, have nobeen tested or approved by Volkswagen

so thawe cannodraw any conclusions aboutheir operation

or suitability.

♦ In order to be filled into an evacuated recycling cylinder withou

any auxiliary equipment, the contaminated refrigeranmusbe

supercooled. The corresponding procedure has been ap‐

proved by Volkswagen and described accordingly

⇒ page 164 .

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CAUTION

Risk of explosion if non-approved equipmenis used

Refrigeranof unknown composition may expand due to a

chemical reaction or overheating causing the used device to

burst.

lk

– Make sure to use only devices and accessories thahave

been authorised and approved by the manufacturer for be‐

ing suitable for operation with gases of unknown composi‐

tion in accordance with the relevanrules and regulations.

– Always read the owner's manual of these devices before

using them.

– Make sure to comply with all instructions given in the re‐

spective owner's manual when using the devices.

CAUTION

Risk of explosion from overfilling refrigeranreservoirs.

Refrigerancan expand and cause reservoirs to bursif they are

overfilled.

– Use a refrigerantank with safety valve.

– Never exceed the permissible fill level of the refrigerantank.

CAUTION

Chemical reactions from contaminated refrigerant. Mixing

gases of unknown composition can cause differenchemical

reactions.

Risk of injuries.

– Never mix toher refrigerants of differenorigins.

Extracrefrigeranof unknown composition from refrigerancircui

and colleciin a recycling cylinder.

– Connect the extracting and charging unito the refrigerancir‐

cuiof the vehicle and to a recycling cylinder observing the

corresponding owner's manual.

– Operate the extracting and charging uniaccording the in‐

structions in the corresponding owner's manual.

– Monitor the extraction process using a suitable pressure

gauge.

Note

♦ You can use your own pressure gauge or the pressure gauge

of the air conditioner service station to monitor the extraction

process.

♦ As iwill take some time until the entire contaminated refrig‐

eranhas been extracted from the refrigerancircuit, make

sure thayou do noswitch off the extracting and charging uni

until the refrigerancircuihas been drained completely. To be

absolutely sure abouthis, watch the display of the connected

pressure gauge.

After the entire contaminated refrigeranhas been extracted from

the circuit:

– Switch off unit.

– Close the manual shut-off valve of the recycling cylinder.

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– Wait a certain amounof time (e.g. 20 minutes), then check if

pressure started building up again in the vehicle’s refrigeran

circuit.

Note

lk

If pressure started building up in the refrigerancircuidue to

evaporation of refrigerant, fill the refrigeranresponsible for this

increase in pressure into the recycling cylinder.

– Remove the charge hose and adapter from the recycling cyl‐

inder, and seal the connection of the recycling cylinder with

the sealing cap.

– The paperwork required for analysis, processing (or disposal)

of contaminated refrigeranmusbe filled in completely (dis‐

posal record, acceptance certificate etc.).

Note

♦ All of the information and documents for analysis, processing

(or disposal) can be obtained from your gas processing / gas

disposal company.

♦ Included with the recycling cylinder is a form. Kindly fill this in

accordingly and attach ito the recycling cylinder.

♦ If iis nopossible to weigh the recycling cylinder before and

after filling with contaminated refrigerant, the fill volume speci‐

fied for the vehicle in question can be quoted as the amoun

of refrigeranthawas filled in the recycling cylinder. This is

permissible as only the amounof refrigeranfrom a vehicle is

filled in a recycling cylinder.

– Take the recycling cylinder to a suitable location for storage

until iis ready to be collected by the gas processing / gas

disposal company.

– Fill outhe data sheefor the recycling cylinder (R-cylinder) if

the refrigeranis contaminated, and firmly attach ito the re‐

cycling cylinder.

Note

♦ In the “Other comments” section, details can be provided re‐

garding e.g. who is to receive the analysis results and in which

way.

♦ Example for recycling cylinder (R-cylinder) data shee

⇒ page 169 .

– Evacuate the refrigerancircuiwith the air conditioner service

station for aleas1 hour

⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

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Note

♦ Subsequenevacuation results in the lasremnants of conta‐

minated refrigerant, which could still be in the refrigeranoil,

being removed aan absolute pressure of less than 10 mbar.

♦ If, after the unihas been switched off, a pressure thais higher

than the maximum permissible pressure for the function

“Evacuate” to be started on the air conditioner service station

builds up in the refrigerancircuit, release this pressure (drain

refrigerant) into the workshop extraction unit.

♦ The nexsteps depend on the complainwith the refrigeran

circui

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

2.13.2

Filling undercooled contaminated refrig‐

eranin a recycling cylinder

Note

♦ To ensure thathe contaminated refrigeranis filled automat‐

ically withousupporting equipmeninto an evacuated recy‐

cling cylinder, the cylinder musbe supercooled.

♦ To cool down the evacuated recycling bottle, use an insulated

container and dry ice.

♦ Dry ice is solid carbon dioxide (CO ) thachanges from a solid

2

lk

directly to a gaseous state a-78°C.

♦ Mosof the gases used as refrigeranhave only a low vapour

pressure avery low temperatures (less than 0.6 bar absolute

pressure a-50°C). When an extremely cooled recycling cyl‐

inder is connected to a refrigerancircuit, the refrigeranliq‐

uefies in the cold recycling cylinder and the pressure in the

refrigerancircuidrops below ambienpressure

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 .

♦ Commercially available recycling cylinders are usually made

of common mild steel. These are noalways suitable for low

temperatures (down to -78°C in this case), which is why only

recycling cylinders suitable for this application should be used

and why the cylinder should be allowed to reach ambientem‐

perature slowly (e.g. by placing the insulated container with

recycling cylinder in a secure, well-ventilated location where

the dry ice can evaporate safely).

Special tools and workshop equipmenrequired

♦ Extraction uni- VAS 581 007- ⇒ Electronic parts

catalogue (ETKA)

♦ At leas10 kg of commercially available dry ice (pellets or

granules)

♦ Evacuated recycling cylinder from gas supplier for contami‐

nated R1234yf refrigerant, which is suitable for very low tem‐

peratures (e.g. with a permissible fill capacity greater than

3.0 kg).

♦ Commercially available bottle adapter with seal (for connect‐

ing charge hose to recycling bottle, internal W 21.8 x 1/14 LH

left-hand thread and M 12 x 1.5-6G in accordance with SAE

J639)

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♦ Commercially available charge hose for R1234yf refrigeran

with seals (2m charge hose with external M12 x 1.5-6G thread

in accordance with SAE J639)

♦ Commercially available low-pressure service coupling in ac‐

cordance with SAE J639

Note

Dry ice evaporates aambientemperature even from the insu‐

lated container (abou20 to 30% per day depending on the

ambienconditions). Therefore, only order the dry ice once all of

the necessary tools are ready and the measures can be per‐

formed immediately after receipof the dry ice (e.g. do noorder

the dry ice on a Friday if work is nogoing to be carried ouathe

weekend).

CAUTION

Risk of frost-bite and suffocation from dry ice.

lk

Frost-bite on the skin and other body parts possible and risk of

suffocation in gaseous state.

– Wear protective gloves.

– Wear protective goggles.

– Only work with dry ice in well ventilated areas.

– Never work in or near cellars or other low lying areas.

CAUTION

Risk of explosion from incorrectly stored dry ice.

As dry ice evaporates, pressure builds up in the container. Un‐

suitable containers could burst.

– Only transporand store dry ice in dedicated containers.

Refilling refrigeranusing a supercooled recycling cylinder

•

All requisite tools, equipmenand a sufficienquantity of dry

ice ready

– Remove seal on recycling cylinder and unscrew sealing cap

from connection.

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Note

♦ Sealed recycling cylinders from your gas supplier usually

come pre-evacuated.

♦ Should the recycling cylinder nobe evacuated, evacuate ias

necessary using a vacuum pump or an air conditioner service

station .

♦ Recycling cylinders are clearly marked as such and, unlike

refrigerancylinders, do nohave a non-return valve thereby

making them suitable for filling.

♦ Recycling cylinders are designed for international use, which

is why the “O” on the handwheel means “Open” (cylinder valve

= open) and no“0” (zero = closed).

♦ If an absolute pressure greater than 100 mbar buless than

900 mbar is measured in the recycling cylinder, evacuate the

recycling cylinder using a vacuum pump (or an air conditioner

service station ) (residual pressure less than 50 mbar)

⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

♦ If an absolute pressure greater than 900 mbar is measured in

the recycling cylinder, this could be due to a number of rea‐

sons. The manual shut-off valve was opened and noclosed

properly or the recycling cylinder had previously been used to

store refrigeranand then was noevacuated properly

⇒ “2.10 Emptying air conditioner service station”, page 154

(evacuate recycling cylinder). The recycling cylinder is leaking

(return the recycling cylinder to the supplier).

lk

– Connect a vacuum metre (or air conditioner service station )

to the recycling cylinder.

– Carefully open the manual shut-off valve of the recycling cyl‐

inder to check the vacuum and then check the vacuum in the

cylinder.

– If necessary, evacuate the recycling cylinder with the air con‐

ditioner service station .

Note

♦ Should there be any air trapped in the recycling cylinder, ican

be evacuated using an air conditioner service station for

R1234yf. To do this, unscrew the low pressure service cou‐

pling from the charge hose of the air conditioner service station

and connecthe charge hose directly to the recycling cylinder

adapter for the extraction device (for R1234yf refrigerant) - dry

ice box .

♦ If air is trapped in the recycling cylinder and there is no air

conditioner service station for R1234yf available, the recycling

cylinder can also be evacuated with an air conditioner service

station for R134a using a relevanflushing container and

adapter -VAS 6338/38- along with the charge hose from ex‐

traction device (for R1234yf refrigerant) - dry ice box .

•

Residual pressure in the recycling cylinder less than 10 mbar

absolute pressure.

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Note

♦ Recycling cylinders are pre-evacuated by the supplier, though

iis noalways possible to ensure thathe vacuum will remain

intacin storage.

♦ To reliably determine the type and scope of the contamination

of the refilled refrigeranduring analysis of the contaminated

refrigerant, the recycling cylinder musbe evacuated before

refilling to a residual pressure less than 50 mbar.

– Switch off ignition.

– Ensure thathe workplace is well ventilated. Switch on addi‐

tional workshop extraction systems if fitted.

– Connect the charge hose with a suitable adapter to the evac‐

uated recycling cylinder.

CAUTION

Risk of explosion from overfilling refrigeranreservoirs.

Refrigerancan expand and cause reservoirs to bursif they are

overfilled.

– Use a refrigerantank with safety valve.

– Never exceed the permissible fill level of the refrigerantank.

lk

Note

♦ Since contaminated refrigeranis only filled into a recycling

cylinder from a vehicle in the following work routine, there is

no danger of a recycling cylinder being overfilled with a fill vol‐

ume exceeding 3.0 kg.

♦ If contaminated refrigeranis filled into a recycling cylinder e.g.

from an air conditioner service station , measures musbe

taken to ensure thathe recycling cylinder is nooverfilled due

to the larger volume. Use a recycling cylinder with an appro‐

priate permissible fill capacity and when refilling ensure by

means of weighing thathe maximum permissible fill volume

is noexceeded.

CAUTION

Chemical reactions from contaminated refrigerant. Mixing

gases of unknown composition can cause differenchemical

reactions.

Risk of injuries.

– Never mix toher refrigerants of differenorigins.

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– Connect the service coupling for R1234yf refrigeran-5- to the

charge hose -4-.

– Connect the charge hose -4- with cylinder adapter -3- (and

seal -2-) to the recycling cylinder -1-.

– Place the spacer -6- in the insulated container -7-.

– Cover the base of the insulated container -7- with dry ice.

– Place the recycling cylinder -1- in the insulated container -7-

extraction device (for R1234yf refrigerant) - dry ice box .

– Pour the remainder of the dry ice in the insulated container

-7-.

– Cool down the recycling container -1- with dry ice (for approx.

15 minutes).

– Connect the recycling cylinder -1- via the service coupling

-5- to the connection of the air conditioner service station (or

the vehicle's refrigerancircuit).

– Open the manual shut-off valve of the recycling cylinder -1-.

Note

Recycling cylinders are designed for international use, which is

why the “O” on the handwheel means “Open” (cylinder valve =

open) and no“0” (zero = closed).

– Connect a pressure gauge to the refrigerancircui(or use the

pressure gauge of the air conditioner service station ) and

check the pressure in the refrigerancircuit.

– Carefully open the service coupling -5- on the charge hose for

the recycling cylinder and allow the refrigeranto flow ou

slowly into the recycling cylinder -1-.

– Wait until the refrigeranin the recycling cylinder -1- has liq‐

uefied (watch the display on the connected pressure gauge).

Note

♦ You can use your own pressure gauge or the pressure gauge

of the air conditioner service station to monitor the extraction

process.

♦ As soon as the displayed pressure is less than 0.3 bar after

approx. 60 minutes, iis safe to assume thathe whole refrig‐

eranin the recycling cylinder is liquefied.

♦ Complete evaporation of the contaminated refrigeranfrom the

refrigerancircuitakes some time. After 60 minutes, iis safe

to assume thathe whole refrigeranhas evaporated.

– Close the service coupling -5- and manual shut-off valve of the

recycling cylinder -1-.

– Remove the charge hose -4- and cylinder connecting piece

-3- from the recycling cylinder -1- and close the recycling cyl‐

inder with the cap.

– The paperwork required for analysis, processing (or disposal)

of contaminated refrigeranmusbe filled in completely (dis‐

posal record, acceptance certificate etc.).

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Note

♦ All of the information and documents for analysis, processing

(or disposal) can be obtained from your gas processing / gas

disposal company.

♦ Included with the recycling cylinder is a form. Kindly fill this in

accordingly and attach ito the recycling cylinder.

♦ If iis nopossible to weigh the recycling cylinder before and

after filling with contaminated refrigerant, the fill volume speci‐

fied for the vehicle in question can be quoted as the amoun

of refrigeranthawas filled in the recycling cylinder. This is

permissible as only the amounof refrigeranfrom a vehicle is

filled in a recycling cylinder.

– Move the insulated box -7- with recycling cylinder -1- and dry

ice to a secure, well ventilated area outside the building.

– Open the lid of the insulated box -7- or remove and allow the

dry ice to evaporate.

Note

Do notake the recycling cylinder -1- ouof the insulated container

-7- until the dry ice has evaporated and the recycling cylinder has

adjusted to ambientemperature.

– Remove the recycling cylinder -1- from the insulated container

-7-.

lk

– Take the recycling cylinder -1- to a suitable location for storage

until iis ready to be collected by the gas processing / gas

disposal company.

– Evacuate the refrigerancircuiwith the air conditioner service

station for aleas1 hour

⇒ “2.5 Evacuating refrigerancircuit”, page 140 .

Note

♦ Subsequenevacuation results in the lasremnants of conta‐

minated refrigerant, which could still be in the refrigeranoil,

being removed aan absolute pressure of less than 10 mbar.

♦ The nexsteps depend on the complainwith the refrigeran

circui

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 .

– Fill outhe data sheefor the recycling cylinder (R-cylinder) if

the refrigeranis contaminated and firmly attach ito the recy‐

cling cylinder -1-.

Note

In the “Other comments” section, details can be provided regard‐

ing e.g. who is to receive the analysis results and in which way.

Example for recycling cylinder (R-cylinder) data shee

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Data sheefor R-cylinder if refrigeranis contaminated

Service contac

Dealership contact:

Email address:

Customer information:

Surname, firsname:

Street:

Town/city:

Vehicle model

Identification

Vehicle identification

number:

Mileage:

Gas analysis performed

on:

Information abouR-cylinder

Cylinder number:

Cylinder weighwith

contents:

(gross weight)

Fill volume

(neweight)

lk

Other comments

2.14

Checking pressures

⇒ “2.14.1 General information on checking pressures in the re‐

frigerancircuit”, page 170

⇒ “2.14.2 Pressures and temperatures in refrigerancircuit”, page

173

⇒ “2.14.3 Checking pressures in the refrigerancircuiwith the

ignition switched off”, page 176

⇒ “2.14.4 Checking pressures with air conditioning system switch‐

ed on - vehicles with mechanical air conditioning compressor”,

page 183 .

⇒ “2.14.5 Checking pressures with air conditioning system switch‐

ed on - vehicles with electrical air conditioning compressor”, page

205

2.14.1

General information on checking pres‐

sures in the refrigerancircui

Note

Work on the refrigerancircuithainvolves the air conditioner

service station can usually be carried ouwithouthe need to de-

energise the high-voltage system.

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Vehicles with electrically-actuated valves in the refrigerancircui

thaare noopen when de-energised:

lk

Note

On vehicles with high-voltage system and auxiliary air condition‐

ing system functions (“heapump mode” or “cooling of high-

voltage battery”), valves may be installed in the refrigerancircui

thaare noopen when de-energised. These valves are opened

and closed e.g. via incremental motors and are no longer actu‐

ated when the ignition is switched off. To check the pressures in

the refrigerancircuiwith the air conditioning system switched off,

however, no areas may be isolated, which is why these valves

musbe opened before work is carried ou⇒ Heating, air condi‐

tioning; Rep. gr. 87 ; Refrigerancircuit; System overview -

refrigerancircuiand ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode.

– Use the vehicle diagnostic tester to open the electrically-ac‐

tuated valves thaare noopen when de-energised ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode.

All vehicles

NOTICE

Risk of damage to the air conditioner compressor or air condi‐

tioner service station.

Opening the valves with the air conditioning system switched

on can cause a shorcircuibetween the high pressure and low

pressure side.

– Never open valves on the high pressure or low pressure side

with the air conditioning system switched on.

Note

♦ Certain conditions for testing are pertinento a certain vehicle

and are described in the vehicle-specific workshop manual ⇒

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu.

♦ Check the cooling outpu⇒ Heating, air conditioning; Rep. gr.

00 ; Repair instructions; Checking cooling outpu(vehicle-spe‐

cific workshop manual).

♦ Connections with valve and service connections for measuring

and testing ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircuit; System overview - refrigerancircui(vehicle-

specific workshop manual)

♦ Depending on the version of air conditioner compressor, a

valve may be installed on the high-pressure side thaprevents

liquefied refrigeranflowing back into the air conditioner com‐

pressor after the air conditioning system is switched off. If an

air conditioner compressor with this valve is installed in a ve‐

hicle with a refrigerancircuiwith expansion valve, icould

take some time before the pressure on the high-pressure side

drops (the expansion valve is cold and the pressure on the

low-pressure side rises quickly after switching off, the expan‐

sion valve closes and refrigeranonly flows slowly on the low-

pressure side). If the air conditioner compressor is switched

on, the pressure on the low-pressure side drops, the expan‐

sion valve opens and refrigerancan flow on the low-pressure

side.

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Under certain operating conditions, residual moisture in the re‐

frigerancircuimay lead to the formation of ice athe air condi‐

tioner compressor regulating valve. The ice impairs the air

conditioner compressor control and causes the evaporator to be

cooled excessively and to ice up. Icing-up of the evaporator may

give rise to the following problems:

♦ Repeated or sporadic failure of the air conditioner (no cooling/

heaoutput) after a lengthy journey. After switching off the en‐

gine and waiting for a shorperiod, operation of air conditioner

returns to normal.

♦ Misting up of the windows on the inside after a long journey;

the windows are initially nocleared even by pressing the De-

frosbutton; the air conditioner functions properly again after

a shordelay following engine shut-off (or after switching off

the air conditioner).

Remedy:

– On vehicles with an air conditioner compressor with air con‐

ditioner compressor regulating valve - N280- , check the

measured value of the evaporator outputemperature sender

- G263- (via the “Read measured values” function). If the

measured value of the sender is too low under the operating

conditions described by the customer (aan ambientemper‐

ature above 0°C, colder than 0°C for an extended period even

though the -N280- is currently noactuated) or too high (higher

than approx. 10°C, even though the air conditioning system is

lk

functioning properly): the evaporator may ice up due to the

incorrecmeasured value ⇒ Vehicle diagnostic tester in “Gui‐

ded FaulFinding” mode - air conditioning system and ⇒

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu(vehicle-specific workshop manual).

– On vehicles withouevaporator outputemperature sender -

G263- , use e.g. the footwell ventemperature sender - G192-

to check the outletemperature with the temperature seto

“low” or “cold” for the driver and fronpassenger side with the

lowessetting (4 or 5 bars) for the fresh air blower speed, air

outlein the footwell and fresh air mode under the operating

conditions described by the customer. If the measured value

of the sender is too low (with an ambientemperature higher

than 0°C, colder than 0°C for an extended period), the evap‐

orator could ice up due to the wrong measured value ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air condi‐

tioning system.

– On vehicles with shut-off valves in the refrigerancircuit, check

the function and actuation of these valves ⇒ Vehicle diagnostic

tester in “Guided FaulFinding” mode - air conditioning sys‐

tem, ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigeran

circuit; System overview - refrigerancircuiand ⇒ Heating,

air conditioning; Rep. gr. 00 ; Repair instructions; Checking

cooling outpu(vehicle-specific workshop manual).

– Check the refrigeranline from the evaporator (or from the in‐

ner heaexchanger) and the air conditioner compressor (thick

pipe, low pressure side) with the engine running. If this line is

very icy when the complainis encountered (a thin layer of ice

is acceptable), this is also evidence thathe temperature in the

evaporator is too low ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircuit; System overview - refrigerancircui(vehi‐

cle-specific workshop manual).

– Empty the refrigerancircuit, renew the receiver with dryer,

renew the reservoir with dryer or desiccancartridge and then

evacuate the refrigerancircuifor aleas3 hours ⇒ Heating,

air conditioning; Rep. gr. 87 ; Refrigerancircuit; System over‐

view - refrigerancircui(vehicle-specific workshop manual)

and ⇒ page 129 .

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♦ ⇒ “2.14.3 Checking pressures in the refrigerancircuiwith the

ignition switched off”, page 176

♦ ⇒ “2.14.4 Checking pressures with air conditioning system

switched on - vehicles with mechanical air conditioning com‐

pressor”, page 183 .

♦ ⇒ “2.14.5 Checking pressures with air conditioning system

switched on - vehicles with electrical air conditioning com‐

pressor”, page 205

2.14.2

Pressures and temperatures in refriger‐

ancircui

General information aboupressures and temperatures in the re‐

frigerancircui⇒ page 173

Pressures and temperatures in refrigerancircuiwith expansion

valve ⇒ page 174

General information aboupressures and temperatures in the re‐

frigerancircui

♦ The pressures and temperatures in the refrigerancircuide‐

pend on the currenoperating conditions (e.g. engine speed,

radiator running alevel 1, 2, or 3, engine temperature, air

conditioner compressor actuation on or off) as well as envi‐

ronmental influences (e.g. ambientemperature, humidity, re‐

quired cooling output).

♦ On vehicles with air conditioner compressor regulating valve -

N280- , the pressure on the low pressure side is varied by

means of -N280- actuation.

lk

♦ For these reasons, the values given in the following table may

only be considered guidelines. They occur aan engine speed

of 1,500 to 2,000 rpm and an ambientemperature of 20°C

after abou20 minutes.

♦ Refer to the vehicle-specific refrigerancircuifor the pressure

gauge semeasuremenconnections ⇒ Heating, air condi‐

tioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific work‐

shop manual).

♦ At 20°C and with the engine stationary, the refrigerancircui

will adjusitself to a pressure of 4.7 bar overpressure

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17 (va‐

pour pressure table).

Note

♦ Pressure is indicated in various units: 1 MPa (Mega-Pascal)

is equal to 10 bar or 145 psi; 1 bar absolute pressure is equal

to 0 bar, which is abouthe same as ambienpressure (at‐

mospheric pressure).

♦ The pressures and temperatures in refrigerancircuits with re‐

strictor and reservoir are abouthe same as those in refriger‐

ancircuits with expansion valve. Since Volkswagen/Audi

currently only installs refrigerancircuits with expansion valve,

justhis refrigerancircuiis described here.

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Pressures and temperatures in refrigerancircuiwith expansion

valve

Note

♦ The following log (p), h-diagram (logarithmic pressure, energy

diagram) shows the processes tharun during certain operat‐

ing conditions in the refrigerancircuit. These values change

depending on the environmental conditions (engine speed,

ambientemperature, requisite cooling output, etc.).

♦ The log (p), h-diagram shows the pressure (0 to 60 in bar ab‐

solute pressure) and the energy conten(100 to 420, specific

enthalpy in kilojoules per kg of R1234yf refrigerant) in the re‐

frigerancircuicycle.

lk

♦ The arrows indicate the direction of refrigeranflow in the re‐

frigerancircuit.

A - Area with vaporous refrigeran

B - Area with gaseous refrigeran

C - Area with liquefied refrigeran

D - Supercritical pressure and temperature range, physical state

of refrigeranundetermined (no longer a separation between liq‐

uefied and gaseous refrigerant)

1 - Low pressure side: outpuof inner heaexchanger, inpuof

air conditioner compressor, refrigeranis completely evapo‐

rated and gaseous, temperature of refrigeranis approx. -4°

C

2 - High pressure side: outpuof air conditioner compressor,

inpuof condenser, refrigeranhas been compressed and is

gaseous, temperature of refrigeranis up to approx. 80°C

3 - High pressure side: outpuof condenser (receiver), inpuof

inner heaexchanger, refrigeranhas been cooled down and

is liquefied, temperature of refrigeranis approx. 55°C

4 - High pressure side: outpuof inner heaexchanger, inpuof

expansion valve, liquefied refrigeranhas cooled down fur‐

ther, temperature of refrigeranis approx. 50°C

5 - Low pressure side: expansion valve on evaporator side, in‐

puof evaporator, liquefied refrigerancomes to resand

starts to evaporate, temperature of refrigeranapprox. -7°C

6 - Low pressure side: outpuof evaporator, expansion valve,

inpuof inner heaexchanger, refrigeranmainly evapora‐

ted, small percentage is still vaporous, temperature of re‐

frigeranapprox. -6°C

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Note

lk

♦ The temperatures given relate to the refrigeranin the refrig‐

erancircuit. The temperatures deviate from this on the sur‐

face of components containing refrigeranowing to hea

absorption and dissipation.

♦ The pressure and the temperature, too, are maintained aap‐

prox. 3 bar absolute pressure (equates to approx. 2 bar over‐

pressure) in refrigerancircuits with regulated air conditioner

compressor despite thermal changes and differenengine

speeds. This applies however only within the rated range of

the air conditioner compressor; if the rated range of the air

conditioner compressor is exceeded, the pressure will in‐

crease and so, too, will the temperature

⇒ “2.14 Checking pressures”, page 170 .

♦ On air conditioner compressors thado noregulate their per‐

formance themselves, the pressure on the low pressure side

and thereby the evaporator temperature are regulated by the

respective control via the air conditioner compressor regulat‐

ing valve - N280- . Depending on the version and the setting,

if an air temperature of less than approx. 2°C is measured after

the evaporator, the performance of the air conditioner com‐

pressor is lowered. Abelow 0°C, -N280- actuation is switched

off. This prevents the evaporator from cooling down too much

and becoming icy.

♦ On vehicles with two evaporators and two expansion valves,

the temperature and pressure in the refrigerancircuiare the

same athe second evaporator as those in vehicles with only

one evaporator and one expansion valve (parallel circuit).

♦ Depending on the version of refrigerancircuit, a componen

with inner heaexchanger may be installed. In the internal hea

exchanger, the holiquid refrigeranflowing on the high pres‐

sure side supplies energy to the cold gaseous or vaporous

refrigeranflowing on the low pressure side, thus enhancing

the efficiency of the air conditioner

⇒ “1.2.13 Refrigeranline with internal heaexchanger”, page

51 .

♦ Depending on the version of control uni(e.g. operating and

display unifor fronair conditioning system - E87- or Clima‐

tronic control uni- J255- ), the measured ambienconditions

(exterior temperature, moisture in the passenger compartmen

etc.) and the control unisetting (passenger compartmentem‐

perature, operating mode etc.), the pressure and thereby also

the temperature athe outpuof the evaporator can also be

regulated aa higher temperature ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system.

2. Working with air conditioner service station

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2.14.3

Checking pressures in the refrigeran

circuiwith the ignition switched off

Tesprerequisites ⇒ page 176

Checking pressures with the ignition switched off ⇒ page 179

Conditions for testing

Note

♦ Work on the refrigerancircuithainvolves the air conditioner

service station (checking the pressures in this case) can usu‐

ally be carried ouwithouthe need to de-energise the high-

voltage system.

♦ Only de-energise the high-voltage system if work on the high-

voltage system is necessary ⇒ page 3

All vehicles

Note

♦ Certain conditions for testing are pertinento a certain vehicle

and are described in the vehicle-specific workshop manual ⇒ ^lk

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu(vehicle-specific workshop manual).

♦ Depending on the version of air conditioner compressor, a

valve may be installed on the high-pressure side thaprevents

liquefied refrigeranflowing back into the air conditioner com‐

pressor after the air conditioning system is switched off. If an

air conditioner compressor with this valve is installed in a ve‐

hicle with a refrigerancircuiwith expansion valve, icould

take some time before the pressure on the high-pressure side

drops (the expansion valve is cold and the pressure on the

low-pressure side rises quickly after switching off, the expan‐

sion valve closes and refrigeranonly flows slowly on the low-

pressure side). If the air conditioner compressor is switched

on, the pressure on the low-pressure side drops, the expan‐

sion valve opens and refrigerancan flow on the low-pressure

side.

♦ Check the cooling outpu⇒ Heating, air conditioning; Rep. gr.

00 ; Repair instructions; Checking cooling outpu(vehicle-spe‐

cific workshop manual).

♦ Connections with valve and service connections for measuring

and testing ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircui(vehicle-specific workshop manual).

♦ Connect the air conditioner service station

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

Under certain operating conditions, residual moisture in the re‐

frigerancircuimay lead to the formation of ice athe air condi‐

tioner compressor regulating valve. The ice impairs the air

conditioner compressor control and causes the evaporator to be

cooled excessively and to ice up. Icing-up of the evaporator may

give rise to the following problems:

♦ Repeated or sporadic failure of the air conditioner (no cooling/

heaoutput) after a lengthy journey. After switching off the en‐

gine and waiting for a shorperiod, operation of air conditioner

returns to normal.

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♦ Misting up of the windows on the inside after a long journey;

the windows are initially nocleared even by pressing the De-

frosbutton; the air conditioner functions properly again after

a shordelay following engine shut-off (or after switching off

the air conditioner).

Remedy:

– On vehicles with an air conditioner compressor with air con‐

ditioner compressor regulating valve - N280- ,_lkcheck the

measured value of the evaporator outputemperature sender

- G263- (via the “Read measured values” function). If the

measured value of the sender is too low under the operating

conditions described by the customer (aan ambientemper‐

ature above 0°C, colder than 0°C for an extended period even

though the -N280- is currently noactuated) or too high (higher

than approx. 10°C, even though the air conditioning system is

functioning properly): the evaporator may ice up due to incor‐

recactuation of -N280- or the incorrecmeasured value of -

G263- ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode - air conditioning system and ⇒ Heating, air condition‐

ing; Rep. gr. 00 ; Repair instructions; Checking cooling outpu

(vehicle-specific workshop manual).

– On vehicles withouevaporator outputemperature sender -

G263- , use e.g. the footwell ventemperature sender - G192-

to check the outletemperature with the temperature seto

“low” or “cold” for the driver and fronpassenger side with the

lowessetting (4 or 5 bars) for the fresh air blower speed, air

outlein the footwell and fresh air mode under the operating

conditions described by the customer. If the measured value

of the sender is too low (with an ambientemperature higher

than 0°C, colder than 0°C for an extended period), the evap‐

orator could ice up due to the wrong measured value ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air condi‐

tioning system.

– On vehicles with shut-off valves in the refrigerancircuit, check

the function and actuation of these valves ⇒ Vehicle diagnostic

tester in “Guided FaulFinding” mode - air conditioning system

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual) and ⇒ Heating, air con‐

ditioning; Rep. gr. 00 ; Repair instructions; Checking cooling

outpu(vehicle-specific workshop manual).

– Check the refrigeranline from the evaporator (or from the in‐

ner heaexchanger) and the air conditioner compressor (thick

pipe, low pressure side) with the engine running. If this line is

very icy when the complainis encountered (a thin layer of ice

is acceptable), this is also evidence thathe temperature in the

evaporator is too low ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual).

– Empty the refrigerancircuit, renew all reservoirs/receivers

with dryer or desiccancartridge and then evacuate the refrig‐

erancircuifor aleas3 hours ⇒ Heating, air conditioning;

Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop

manual) and

⇒ “2 Working with air conditioner service station”, page 129 .

Conditions for testing

♦ Observe the general information on checking pressures in the

refrigerancircui

⇒ “2.14.1 General information on checking pressures in the

refrigerancircuit”, page 170

2. Working with air conditioner service station

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Note

All of the conditions for testing marked with * are pertinento a

certain vehicle and are described in the vehicle-specific workshop

manual ⇒ Heating, air conditioning; Rep. gr. 00 ; Repair instruc‐

tions; Checking cooling outpu(vehicle-specific workshop man‐

ual).

General conditions for testing (these only have an influence on

the display of the pressure gauges during this measuremenwith

the air conditioning system switched on)

•

Radiator and condenser are clean (clean them if necessary).*

The heainsulation on the expansion valve is OK and properly

installed.*

•

The poly V-belis OK and properly tensioned. The belts for air

conditioner compressor and alternator are in good condition

and correctly tensioned.*

The drive unifor the air conditioner compressor is OK and

properly installed.*

•

All air ducts, covers and seals are OK and properly installed.*

Diagnosis of the air conditioning system finds no faults (with

the engine running and the air conditioning system switched

on), no compressor deactivation conditions are shown in the

measured values (only on vehicles with diagnosis “air condi‐

tioning system”).* ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode of air conditioning system.

•

The air flow rate through the dusand pollen filter is noim‐

paired by dirt.*

All dash panel air vents are open.*

lk

Note

♦ Depending on the engine, the air conditioner compressor is

driven by differencomponents (belts or drive shaft). To pro‐

tecthese components and the engine, the pulley or the air

conditioner compressor drive uniis fitted with an overload

protection which is tripped if the air conditioner compressor is

nooperating smoothly ⇒ Heating, air conditioning; Rep. gr.

00 ; Repair instructions; Checking cooling outpu(vehicle-spe‐

cific workshop manual) and ⇒ Heating, air conditioning; Rep.

gr. 87 ; Air conditioner compressor (vehicle-specific workshop

manual).

♦ On certain versions, the radiator fan cuts in only after the pres‐

sure in the refrigerancircuihas exceeded a pre-sevalue

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system.

Other conditions for testing (these have an influence on the dis‐

play of the pressure gauge with this measurement)

•

The vehicle is noexposed to the sun's rays ⇒ Heating, air

conditioning; Rep. gr. 00 ; Repair instructions; Checking cool‐

ing outpu(vehicle-specific workshop manual).

•

Ambientemperature is above 15°C.

The ignition is switched off.

The air conditioner service station is connected to the refrig‐

erancircui

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⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

♦ ⇒ “2.14.4 Checking pressures with air conditioning system

switched on - vehicles with mechanical air conditioning com‐

pressor”, page 183 .

lk

♦ ⇒ “2.14.5 Checking pressures with air conditioning system

switched on - vehicles with electrical air conditioning com‐

pressor”, page 205

Checking pressures with the ignition switched off

Note

♦ The switching pressures for actuation of the air conditioner

compressor regulating valve - N280- , the air conditioning sys‐

tem magnetic clutch - N25- (if fitted) and the radiator fan (e.g.

radiator fan - V7- / radiator fan 2 - V177- ) are vehicle-specific

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system.

♦ The pressures musbe measured athe service connections;

the fitting locations of these connections are vehicle-specific

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

♦ Once the planned measures are complete, separate the air

conditioner service station from the refrigerancircuiand

switch ioff

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

•

The engine is aoperating temperature (aan ambientem‐

perature less than 25°C).

Note

♦ Should the engine nobe aoperating temperature, take the

vehicle for a shordrive.

♦ To testhe cooling output, the engine does nohave to be a

operating temperature. However, to demand a certain cooling

outpufrom the air conditioning system aan ambientemper‐

ature of less than 25°C, the engine is required to be warm if

ambientemperatures are low.

♦ Observe the tesprerequisites ⇒ page 176 .

– On vehicles with high-voltage system, switch off “stationary air

conditioning” function (deactivate)⇒ Owner's Manual and ⇒

Operating instructions of infotainmen/ MMI .

– Switch off ignition.

– Connect the air conditioner service station

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

– Check the pressures in the refrigerancircuiwith the engine

stationary.

– Take pressure readings from pressure gauges of air condi‐

tioner service station . Two results may be displayed:

♦ The pressure in the refrigerancircuiis lower than indicated

in the following table ⇒ page 182 .

♦ The pressure in the refrigerancircuiis equal to or greater than

thain the following table ⇒ page 183 .

2. Working with air conditioner service station

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Note

♦ Vapour pressure table for R1234yf refrigeran

⇒ “6.1.3 Vapour pressure table for refrigerant”, page 17

♦ On vehicles with high-voltage system and auxiliary air condi‐

tioning system functions (“heapump mode” or “cooling of

high-voltage battery”), valves may be installed in the refriger‐

ancircuithaare noopen when de-energised. These valves

are opened and closed e.g. via incremental motors and are no

longer actuated when the ignition is switched off. Depending

lk

on the lasoperating status of the air conditioning system, cer‐

tain areas of the refrigerancircuicould be isolated by these

valves. Depending on the layouof the service connections in

the refrigerancircuit, these could be in an area thais isolated

(e.g. the area with the service connection on the high pressure

side). If necessary, these valves musbe opened before the

pressure is tested ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual) and

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode.

♦ The pressures given in the table are slightly lower than speci‐

fied in the vapour pressure table for the R1234yf refrigerant.

The evaporation pressure of the refrigeranin the refrigeran

circuiis orientated around the coldescomponenand could

therefore also be slightly lower in a correctly charged refriger‐

ancircuithan thaspecified for the R1234yf refrigeranin the

vapour pressure table.

Ambientemperature (in de‐ Pressure in the refrigerancir‐

grees C)

+15 °C

+20 °C

+25 °C

+30 °C

+35 °C

+40 °C

+45 °C

cuiin bar positive pressure

3.5

4.4

5.3

6.3

7.4

8.6

10.0

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Note

♦ The temperature of the components of the refrigerancircui

should be the same as the ambientemperature. If individual

components of the refrigerancircuiare warmer or colder, the

pressure will deviate from the values shown in the tables.

♦ Absolute pressure means tha0 bar corresponds to an abso‐

lute vacuum. The normal ambienpressure corresponds to 1

bar absolute pressure. On mospressure gauges, a reading

of 0 bar corresponds to an absolute pressure of one bar (which

is confirmed by the existence of a -1 bar marking beneath the

0 scale marking).

♦ On vehicles with pressure senders ( high pressure sender -

G65- , pressure sender for refrigerancircui- G805- or refrig‐

eranpressure and temperature sender - G395- , etc.) for

which the measured pressure is displayed in the measured

values of the diagnosis, the measured pressure should corre‐

late with the values in the table (or be slightly higher) ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air condi‐

tioning system and ⇒ Heating, air conditioning; Rep. gr. 00 ;

Repair instructions; Checking cooling outpu(vehicle-specific

workshop manual).

lk

♦ The pressure is given in differenunits, 1 MPa (megapascal)

equates to 10 bar overpressure or 145 psi. A0 bar overpres‐

sure, 1 bar absolute pressure is approximately the same as

ambienpressure (atmospheric pressure).

If the measured values are OK and there is no complaint:

– Unscrew (close) the handwheels of the quick-release coupling

adapters ⇒ Operating instructions air conditioner service sta‐

tion .

– Extract the refrigeranfrom the two charge hoses using the air

conditioner service station as instructed in the relevanoper‐

ating manual ⇒ Operating instructions air conditioner service

station .

– Switch off the air conditioner service station (and isolate ifrom

the power supply if necessary)

⇒ “2.8 Switching off air conditioner service station and sepa‐

rating from refrigerancircuit”, page 151 .

If the measured values are OK and there is complaint:

– Check the cooling outpuof the air conditioning system ⇒

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu(vehicle-specific workshop manual)

and watch the pressures in the refrigerancircuit.

♦ ⇒ “2.14.4 Checking pressures with air conditioning system

switched on - vehicles with mechanical air conditioning com‐

pressor”, page 183 .

♦ ⇒ “2.14.5 Checking pressures with air conditioning system

switched on - vehicles with electrical air conditioning com‐

pressor”, page 205

If the measured values are noOK:

– Investigate the cause of the deviation and rectify.

2. Working with air conditioner service station

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Note

♦ If the pressures are too low, icould be because there is too

little refrigeranin the circui⇒ Heating, air conditioning; Rep.

gr. 00 ; Technical data (vehicle-specific workshop manual)

and ⇒ “2.4 Emptying refrigerancircuit”, page 137 .

♦ If the pressures are too high, there may be too much refriger‐

anor refrigeranoil in the circuit. Empty the refrigerancircui

using the air conditioner service station

⇒ “2.4 Emptying refrigerancircuit”, page 137 . If the extracted

refrigeranvolume is greater than the specified fill capacity for

the R1234yf refrigeran⇒ Heating, air conditioning; Rep. gr.

00 ; Technical data (vehicle-specific workshop manual), evac‐

uate the refrigerancircuiand recharge with the correc

amounof R1234yf refrigerant. Then repeathe test. If the ex‐

tracted quantity of refrigeranroughly equates to the specified

fill capacity for the R1234yf refrigeranor is less, clean the re‐

frigerancircuiwith refrigeran

lk

⇒ “1.6 Cleaning refrigerancircuit”, page 92 . Then add the

specified amounof refrigeranoil, evacuate the refrigeran

circuit, recharge with the correcvolume of R1234yf refrigeran

and repeathe test.

♦ If the pressures are too low or too high and contaminated re‐

frigeranis found during the gas analysis, this may be the

cause of the deviation (differenrefrigerants have varying va‐

pour pressures). Empty the refrigerancircuiand then clean

with R1234yf refrigeran

⇒ “2.3 Performing gas analysis of refrigerant”, page 134 ,

⇒ “2.4 Emptying refrigerancircuit”, page 137 and

⇒ “1.6 Cleaning refrigerancircuit”, page 92

The pressure in the refrigerancircuiis lower than indicated in

the table

Too little refrigeranin circuit.

– Check for leaks in the refrigerancircui

⇒ “1.4 Investigating leaks”, page 68 .

– Check the high pressure safety valve

⇒ “1.2.17 High-pressure safety valve”, page 53 .

If the high pressure safety valve has blown (check

⇒ “1.2.17 High-pressure safety valve”, page 53 ):

– Check radiator fan actuation or the radiator fan ⇒ Vehicle di‐

agnostic tester in “Guided FaulFinding” mode - air condition‐

ing system.

– On vehicles with shut-off valves for the refrigerancircuit,

check the actuation and function of these shut-off valves ⇒ Ve‐

hicle diagnostic tester in “Guided FaulFinding” mode - air

conditioning system (and battery control) and ⇒ Heating, air

conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual).

– Check refrigeranlines and refrigeranhoses for signs of

crushing (bottle-neck), external damage and tighbends ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(ve‐

hicle-specific workshop manual) and ⇒ Heating, air condi‐

tioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual).

– If no faulcan be detected, clean the refrigerancircui

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

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The pressure in the refrigerancircuiis equal to or greater than

thain the table

♦ ⇒ “2.14.4 Checking pressures with air conditioning system

switched on - vehicles with mechanical air conditioning com‐

pressor”, page 183 .

♦ ⇒ “2.14.5 Checking pressures with air conditioning system

switched on - vehicles with electrical air conditioning com‐

pressor”, page 205

2.14.4

Checking pressures with air condition‐

ing system switched on - vehicles with

mechanical air conditioning compressor

lk

Checking pressures ⇒ page 183

Specifications for pressures in the refrigerancircui

⇒ page 187

Checking pressures

Refrigerancircuiwith expansion valve, receiver with or withou

air conditioning system magnetic clutch - N25- and air conditioner

compressor regulating valve - N280- (with externally regulated air

conditioner compressor)

Note

♦ Connecthe air conditioner service station

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

♦ If on vehicles with two evaporators a problem is encountered

in jusone evaporator, check the pressures in the refrigeran

circuit. If these are OK, check the line connection between the

evaporator thais causing the problem and the outleof the

line connection athe distribution poinof the refrigeranlines

(for bottle-neck or blockage). If no faulcan be determined,

empty the refrigerancircuiand recharge with the prescribed

amounof refrigerant. Then check the pressures and the cool‐

ing outpuof the air conditioner again. If the problem persists,

replace the expansion valve upstream of the problematic

evaporator ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircui(vehicle-specific workshop manual).

♦ ⇒ “2.14.3 Checking pressures in the refrigerancircuiwith the

ignition switched off”, page 176

Conditions for testing

•

The air conditioner service station is connected to the refrig‐

erancircui

⇒ “2.2 Connecting air conditioner service station to refrigeran

circuit”, page 131 .

•

Observe the conditions for testing pressures in the refrigeran

circuiwith the ignition switched off ⇒ page 176 .

The pressures in the refrigerancircuicomply with the speci‐

fications with the ignition switched off

⇒ “2.14.3 Checking pressures in the refrigerancircuiwith the

ignition switched off”, page 176 .

•

Observe the conditions for testing the cooling outpu⇒ Heat‐

ing, air conditioning; Rep. gr. 00 ; Repair instructions; Check‐

ing cooling outpu(vehicle-specific workshop manual).

2. Working with air conditioner service station

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Note

♦ The switching pressures for actuation of the air conditioner

compressor regulating valve - N280- , the air conditioning sys‐

tem magnetic clutch - N25- (if fitted) and the radiator fan - V7-

are vehicle-specific ⇒ Vehicle diagnostic tester in “Guided

FaulFinding” mode - air conditioning system.

♦ The pressures musbe measured athe service connections;

the fitting locations of these connections are vehicle-specific

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

•

The engine is aoperating temperature (aan ambientem‐

perature less than 25°C).

Note

♦ Should the engine nobe aoperating temperature, take the

vehicle for a shordrive.

♦ To testhe cooling output, the engine does nohave to be a

operating temperature. However, to demand a certain cooling

outpufrom the air conditioning system aan ambientemper‐

ature of less than 25°C, the engine is required to be warm if

ambientemperatures are low.

lk

– Start engine.

– Set the air conditioning system to maximum cooling outpu⇒

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu(vehicle-specific workshop manual).

•

The air conditioner compressor is actually driven with the en‐

gine running (visual check ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerancircui(vehicle-specific workshop man‐

ual)).

•

The air conditioner compressor regulating valve - N280- is ac‐

tuated ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode - air conditioning system.

Note

♦ Depending on the engine, the air conditioner compressor is

driven by differencomponents (belts or drive shaft). To pro‐

tecthese components and the engine, the pulley or the air

conditioner compressor drive uniis fitted with an overload

protection which is tripped if the air conditioner compressor is

nooperating smoothly ⇒ Heating, air conditioning; Rep. gr.

87 ; Air conditioner compressor (vehicle-specific workshop

manual).

♦ On vehicles with air conditioner compressor regulating valve -

N280- , the control currencan be gleaned from the measured

values ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode - air conditioning system.

If the air conditioner compressor is nodriven or the regulating

valve noactivated when the engine is running:

– Determine the cause, e.g. by interrogating the evenmemory

of the air conditioning system, and rectify i⇒ Vehicle diag‐

nostic tester in “Guided FaulFinding” mode - air conditioning

system.

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– If fitted, check the voltage supply for the air conditioning sys‐

tem magnetic clutch - N25- . If this is OK, repair the magnetic

clutch ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigeran

circui(vehicle-specific workshop manual).

– Check actuation of the air conditioner compressor regulating

valve - N280- ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system.

lk

Note

♦ On air conditioner compressors with an air conditioning sys‐

tem magnetic clutch - N25- , the air conditioner compressor

only works (delivers refrigerant) if in addition to the air condi‐

tioner compressor regulating valve - N280- , -N25- is actuated

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system.

♦ -N280- (and -N25- ) is actuated by the air conditioning system

control uni- J301- , the operating and display unifor fronair

conditioning system - E87- and the Climatronic control uni-

J255- or a downstream control uni⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system and

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

♦ All of the conditions for testing marked with * are pertinento

a certain vehicle and are described in the vehicle-specific

workshop manual ⇒ Heating, air conditioning; Rep. gr. 00 ;

Repair instructions (vehicle-specific workshop manual) and ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(ve‐

hicle-specific workshop manual).

•

The radiator and condenser are clean (clean if necessary) * ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(ve‐

hicle-specific workshop manual).

The heainsulation on the expansion valve is OK and mounted

correctly * ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircui(vehicle-specific workshop manual).

The poly V-belis OK and properly tensioned. The belts for air

conditioner compressor and alternator are in good condition

and correctly tensioned.* ⇒ Heating, air conditioning system;

Rep. gr. 87 ; Air conditioner compressor (vehicle-specific

workshop manual) and ⇒ Heating, air conditioning system;

Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop

manual).

•

The drive unifor the air conditioner compressor is OK and

mounted properly * ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual) and ⇒

Heating, air conditioning; Rep. gr. 87 ; Air conditioner com‐

pressor (vehicle-specific workshop manual).

•

The air ducts, covers and seals are OK and mounted correctly

* ⇒ Heating, air conditioning; Rep. gr. 87 ; Overview of fitting

locations - air conditioning system (vehicle-specific workshop

manual).

Diagnosis of the air conditioning system finds no faults (with

the engine running and the air conditioning system switched

on), no compressor deactivation conditions are shown in the

measured values of the respective control uni(only on vehi‐

cles with diagnosis “air conditioning system”).* ⇒ Vehicle di‐

agnostic tester in “Guided FaulFinding” mode of air

conditioning system.

•

The air flow rate through the dusand pollen filter is noim‐

paired by dirt.* ⇒ Heating, air conditioning system; Rep. gr.

2. Working with air conditioner service station

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87 ; Overview of fitting locations - air conditioning system (ve‐

hicle-specific workshop manual).

•

The heater and air conditioner does nodraw any secondary

air ahighesfresh air blower speed. The evaporator and heat‐

er are nodrawing in secondary air athe highesfresh air

lk

blower speed * ⇒ Heating, air conditioning; Rep. gr. 87 ;

Overview of fitting locations - air conditioning system (vehicle-

specific workshop manual).

The air flaps in the heating and air conditioning unit, in the

heating and in the evaporator reach their end position * ⇒

Heating, air conditioning; Rep. gr. 00 ; Repair instructions;

Checking cooling outpu(vehicle-specific workshop manual)

and ⇒ Heating, air conditioning; Rep. gr. 87 ; Overview of

fitting locations - air conditioning system (vehicle-specific

workshop manual).

•

The fresh air intake ducts under the bonneand in the pas‐

senger compartmenand the corresponding water drain

valves are OK * ⇒ Heating, air conditioning; Rep. gr. 00 ;

Repair instructions; Checking cooling outpu(vehicle-specific

workshop manual) and ⇒ Heating, air conditioning; Rep. gr.

87 ; Overview of fitting locations - air conditioning system (ve‐

hicle-specific workshop manual).

•

Engine warm.

The vehicle is noexposed to the sun's rays ⇒ Heating, air

conditioning; Rep. gr. 00 ; Repair instructions; Checking cool‐

ing outpu(vehicle-specific workshop manual).

•

Ambientemperature is above 15°C.

All dash panel diffusers are open * ⇒ Heating, air conditioning;

Rep. gr. 87 ; Air ducsystem (vehicle-specific workshop man‐

ual).

Setting e.g. on operating and display unifor fronair conditioning

system - E87- and Climatronic control uni- J255- or air condi‐

tioning system control uni- J301- (and operating and display uni

for rear Climatronic - E265- on vehicles with two heating and air

conditioning units) * ⇒ Heating, air conditioning; Rep. gr. 00 ;

Repair instructions; Checking cooling outpu(vehicle-specific

workshop manual) and ⇒ Heating, air conditioning; Rep. gr. 87 ;

Overview of fitting locations - air conditioning system (vehicle-

specific workshop manual).

Setting on -E87- / -J255- *: ⇒ Heating, air conditioning; Rep. gr.

00 ; Repair instructions; Checking cooling outpu(vehicle-specific

workshop manual) and ⇒ Heating, air conditioning; Rep. gr. 87 ;

Overview of fitting locations - air conditioning system (vehicle-

specific workshop manual).

– Select “Auto” mode (air conditioner compressor switched on).

– Set temperature to “cold” or “LO” for the driver and fronpas‐

senger side (and the rear on the lefand righin vehicles with

two heating and air conditioning units).

Setting on -J301- *:

– Press A/C button and Rec or recirculate buttons.

– Turn rotary temperature knob in direction of “cold” stop.

– Set rotary fresh air blower switch to “4” (maximum fresh air

blower speed).

The following conditions for testing should then be mein the sys‐

tem:

•

The radiator fan - V7- is running or the radiator fan - V7- and

radiator fan 2 - V177- are running (aleasstage 1) * ⇒ Heat‐

ing, air conditioning; Rep. gr. 00 ; Repair instructions; Check‐

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ing cooling outpu(vehicle-specific workshop manual) and ⇒

Heating, air conditioning; Rep. gr. 87 ; Overview of fitting lo‐

cations - air conditioning system (vehicle-specific workshop

manual).

Note

On certain versions, the radiator fan cuts in only after the pressure

in the refrigerancircuihas exceeded a pre-sevalue ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air conditioning

system.

lk

•

The fresh air blower - V2- (and the rear fresh air blower - V80-

on vehicles with two heating and air conditioning units) is

running amaximum speed.*

•

The coolanshut-off valve is closed * ⇒ Heating, air condi‐

tioning; Rep. gr. 00 ; Repair instructions; Checking cooling

outpu(vehicle-specific workshop manual) and ⇒ Heating, air

conditioning; Rep. gr. 87 ; Overview of fitting locations - air

conditioning system (vehicle-specific workshop manual).

•

The valves of the pump-valve uniare closed and the coolan

circulation pump is nodelivering * ⇒ Heating, air conditioning;

Rep. gr. 00 ; Repair instructions; Checking cooling outpu

(vehicle-specific workshop manual) and ⇒ Heating, air con‐

ditioning; Rep. gr. 87 ; Overview of fitting locations - air

conditioning system (vehicle-specific workshop manual).

•

The fresh air blower - V2- (and the rear fresh air blower - V80-

on vehicles with two heating and air conditioning units) is

running amaximum speed.*

The air recirculation flap/fresh air flap is in “recirculation

mode” (within 1 minute after starting the vehicle, the air flow

flap closes and the air recirculation flap opens).*

•

The coolanshut-off valve is closed.*

The valves for the pump-valve uniare closed and the coolan

circulation pump is nodelivering.*

Specifications for pressures in the refrigerancircui

♦ Observe the conditions for testing and the pressures

⇒ page 183 .

Testing:

– Raise engine speed to 2000 rpm.

– Observe pressure display (e.g. pressure gauge) of air condi‐

tioner service station ⇒ Operating instructions of air condi‐

tioner service station .

Note

♦ The switching pressures for actuation of the air conditioner

compressor regulating valve - N280- and the radiator fan are

vehicle-specific ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system.

♦ The pressures musbe measured athe service connections;

the fitting locations of these connections are vehicle-specific

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

2. Working with air conditioner service station

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High-pressure side:

Rising from starting pressure (when pressure gauge is connec‐

ted) to maximum 20 bar.

Low-pressure side:

From the outpupressure (when connecting the pressure gauge)

dropping to a value of between 1.5 and 2.3 bar absolute pressure

(depending on required cooling output).

lk

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lk

Note

♦ In the evenof a very high cooling outpu(e.g. ahigh outside

temperatures and high fresh air blower speed while the engine

is running slowly), the air conditioner compressor is initially

incapable of changing the pressure on the low pressure side

to the specified level (e.g. for a certain period after switching

on the air conditioning system). The air conditioner compres‐

sor is actuated with the maximum specified control current.

However, the delivery volume of the air conditioner compres‐

sor is noenough under these operating conditions and athis

engine speed to lower the pressure on the low pressure side

to the specification. One way of checking the regulating be‐

haviour of the air conditioner compressor under these condi‐

tions is to actuate e.g. the fresh air blower with only approx.

40% of the maximum voltage and to check the pressures a

reduced fresh air blower speed ⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode - air conditioning system and ⇒

Heating, air conditioning; Rep. gr. 00 ; Repair information;

Checking cooling outpu(vehicle-specific workshop manual).

♦ If the demand on the cooling outpuis low (e.g. aan ambien

temperature of 20°C and a low fresh air blower speed), pres‐

sure on the high pressure side may only increase up to a value

of 6 to 7 bar (the energy exchange is low, the refrigeranis

cooled down quickly in the condenser). To check the regulat‐

ing behaviour and the pressures in the refrigerancircuiunder

these conditions, e.g. actuate the fresh air blower with maxi‐

mum voltage, sethe air conditioning system to maximum

heating outpuand activate air recirculation ⇒ Vehicle diag‐

nostic tester in “Guided FaulFinding” mode - air conditioning

system and ⇒ Heating, air conditioning; Rep. gr. 00 ; Repair

instructions; Checking cooling outpu(vehicle-specific work‐

shop manual).

♦ Under unfavourable conditions (very high ambientempera‐

tures, high atmospheric humidity), the pressure on the high

pressure side can increase to a maximum of 29 bar.

♦ The specified working currenfor the air conditioner compres‐

sor regulating valve - N280- is displayed as a measured value

by the operating and display unifor fronair conditioning sys‐

tem - E87- , the air conditioning system control uni- J301- and

the Climatronic control uni- J255- ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system.

♦ The high pressure measured by the high pressure sender -

G65- , the pressure sender for refrigerancircui- G805- and

the refrigeranpressure and temperature sender - G395- is

displayed as a measured value by -E87- , -J301- or -J255-

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system.

♦ The low pressure adjusts depending on the control currenfor

the air conditioner compressor regulating valve - N280- and

the control characteristic of the expansion valve within the

performance band of the air conditioner compressor in the tol‐

erance range ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system.

♦ In unfavourable conditions (very high ambientemperatures,

high air humidity), the performance of the air conditioner com‐

pressor may noalways be enough to reach the specified

pressure value within the given time (icould take slightly lon‐

ger, depending on the engine speed, for the prescribed low

pressure to be reached).

2. Working with air conditioner service station

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♦ If the air conditioner compressor's capacity utilisation is above

90%, pressure on the low pressure side could be higher than

the specified tolerance range. The air conditioner compressor

outpuis no longer sufficienin the prevailing conditions (am‐

bientemperature, air humidity, setting of the air conditioning

system, engine speed, etc.) to change the pressure on the low

pressure side to approx. 2 bar.

♦ The specified working currenfor the air conditioner compres‐

sor regulating valve - N280- musbe higher than 0.3 A so tha

-N280- can be actuated reliably ⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode - air conditioning system.

♦ When setting to “maximum cooling output”, the control curren

for the air conditioner compressor regulating valve - N280- is

regulated aapprox. 0.65 A (to 0.85 A). This measured value

is vehicle-specific and is displayed in the ⇒ Vehicle diagnostic

tester in “Guided FaulFinding” mode - air conditioning sys‐

tem.

♦ Absolute pressure means tha0 bar corresponds to an abso‐

lute vacuum. The normal ambienpressure corresponds to 1

bar absolute. On mospressure gauges, a reading of 0 bar

corresponds to an absolute pressure of 1 bar (which is con‐

firmed by the existence of a -1 bar marking beneath the 0 scale

marking). Depending on the respective control universion,

pressure can be displayed as a measured value based on ab‐

solute or relative pressure (difference between displays 1 bar)

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system and ⇒ Heating, air conditioning; Rep.

gr. 00 ; Repair instructions; Checking cooling outpu(vehicle-

specific workshop manual).

♦ The temperature of the air after the evaporator, the currenair

conditioner compressor speed and the pressure of the refrig‐

eranon the high pressure side along with the specified work‐

ing currenfor the air conditioner compressor regulating valve

- N280- are displayed e.g. as a measured value by the oper‐

ating and display unit, the Climatronic control uni- J255-

⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode -

air conditioning system.

Possible deviations from specification,

cause and rectification

♦ The required cooling outpuis no

reached.

⇒ page 192

♦ High pressure remains constanor in‐

creases only slightly (above the pressure

measured when the engine is station‐

ary).

♦ Low pressure drops quickly to the spec‐

ification or lower.

♦ The required cooling outpuis no

reached.

⇒ page 193

♦ The high pressure equates to the speci‐

fication

♦ The low pressure equates to the specifi‐

cation or is too low

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Possible deviations from specification,

cause and rectification

♦ The requisite cooling outpuis no

reached.

⇒ page 194

⇒ page 195

♦ High pressure does noincrease or only

marginally above the pressure with the

engine stationary

♦ The low pressure does nodrop or only

marginally

♦ The requisite cooling outpuis no

reached.

♦ The high pressure increases beyond the

specified value

♦ Low pressure drops quickly to the spec‐

ification or lower.

♦ The requisite cooling outpuis reached ⇒ page 196

initially buafter a while or after an ex‐

tended period, the cooling outpuis no

longer sufficient.

lk

♦ The high pressure and the low pressure

are normal to starwith

♦ After some time, the high pressure rises

above the specification, the low pressure

still equates to the specification or i

drops below the specification.

♦ The requisite cooling outpuis reached ⇒ page 198

initially buafter a shoror extended pe‐

riod, the required level is no longer

reached.

♦ The high pressure and low pressure are

normal to starwith buafter a while, the

high pressure rises above the specifica‐

tion and the low pressure drops to the

specification or lower.

♦ The high pressure and low pressure are

normal to starwith. After a while, the low

pressure drops to the specification or

lower and the evaporator ices up.

♦ The requisite cooling outpuis reached. ⇒ page 199

♦ The high pressure equates to the speci‐

fication

♦ The low pressure is too low (lower than

the specification)

♦ The air conditioner compressor is noisy ⇒ page 201

(especially immediately after being

switched on),

♦ The requisite cooling outpuis reached.

♦ High pressure normal or too high

♦ The low pressure is normal or too high

(the specification is noalways reached)

2. Working with air conditioner service station

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Possible deviations from specification,

cause and rectification

lk

♦ The required cooling outpuis no

reached.

⇒ page 203

♦ The high pressure and low pressure

equate to the specification

Possible deviation from specification during pressure tes

♦ The required cooling outpuis noreached.

♦ High pressure remains constanor increases only slightly (above the pressure measured when the engine

is stationary).

♦ The low pressure does nodrop or only marginally

Possible causes for deviation from specification and rectification

♦ Actuation of the air conditioner compressor regulating valve - N280- is defective.

– Check actuation of the air conditioner compressor regulating valve - N280- and repair if necessary ⇒ Vehicle

diagnostic tester in “Guided FaulFinding” mode - air conditioning system.

♦ Air conditioner compressor regulating valve - N280- or air conditioner compressor defective

– Check function of -N280- ; if necessary remove -N280- and check for dir⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode - air conditioning system and ⇒ page 79

– -N280- or renew the air conditioner compressor ⇒ page 79

– If diris found in the refrigerancircuit, clean the refrigerancircui(flush with R1234yf refrigerant) and renew

the expansion valve and desiccanbag/desiccancartridge (or renew the receiver/reservoir) ⇒ page 79 and

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop manual) as well as

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

Final measures

– Recharge the refrigerancircui⇒ “2.6 Charging refrigerancircuit”, page 146

– Repeat the tes

⇒ “2.14.4 Checking pressures with air conditioning system switched on - vehicles with mechanical air

conditioning compressor”, page 183

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Note

♦ If this problem is encountered, ensure thathe air conditioner

compressor (air conditioner compressor shaft) is actually be‐

ing driven via the pulley/drive uni⇒ Heating, air conditioning;

Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop

manual) and ⇒ Heating, air conditioning; Rep. gr. 87 ; Re‐

frigerancircui(vehicle-specific workshop manual).

♦ If no faulcan be found for this complaint, clean the refrigeran

circui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

♦ Check the measured values of the evaporator outputemper‐

ature sender - G263- and actuation of -N280- . If the measured

value of -G263- is faulty, the evaporator could ice up or the

cooling outpumay nobe reached ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system.

♦ If, after repeating the teswhen the expansion valve has been

renewed, the air conditioning system is nooperating correctly,

clean the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 . Then renew the

air conditioner compressor and desiccaninsert/desiccancar‐

tridge (or reservoir/receiver) ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerancircui(vehicle-specific workshop manual).

♦ In this case, the evaporator may ice up even though the correc

volume of refrigeranis presenin the refrigerancircuit.

♦ If the expansion valve is defective (always closed or noopen‐

ing wide enough), -N280- will change to maximum power and

the low pressure will fall to the diagram value or less (the air

conditioner compressor is drawing the refrigeranouof the

low pressure side) ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system. However, since no

refrigerancan flow through the expansion valve, the required

cooling outpuis noreached, the high pressure may also no

rise or only marginally since no energy exchange is taking

place.

lk

Possible deviation from specification during pressure tes

♦ The required cooling outpuis noreached.

♦ The high pressure equates to the specification

♦ The low pressure equates to the specification or is too low

Possible causes for deviation from specification and rectification

♦ There is too little refrigeranin the refrigerancircuit.

♦ The expansion valve is defective.

– Extract refrigeranfrom the refrigerancircui⇒ “2.4 Emptying refrigerancircuit”, page 137 .

– If the extracted refrigeranvolume is considerably less than the specified fill volume (more than 100 g less)

⇒ Heating, air conditioning; Rep. gr. 00 ; Technical data (vehicle-specific workshop manual), search for

the leak and rectify the cause ⇒ “1.4 Investigating leaks”, page 68

– The extracted refrigeranvolume approximately equates to the prescribed fill volume, renew the expansion

valve for the evaporator in the heater and air conditioning uni⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual)

Final measures

2. Working with air conditioner service station

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lk

Possible deviation from specification during pressure tes

– Recharge the refrigerancircui⇒ “2.6 Charging refrigerancircuit”, page 146

– Repeat the tes

⇒ “2.14.4 Checking pressures with air conditioning system switched on - vehicles with mechanical air

conditioning compressor”, page 183

Note

♦ Check the measured values of the evaporator outputemper‐

ature sender - G263- and actuation of -N280- . If the measured

value of -G263- is faulty, the evaporator could ice up or the

cooling outpumay nobe reached ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system.

♦ If, after repeating the teswhen the expansion valve has been

renewed, the air conditioning system is nooperating correctly,

clean the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 . Then renew the

air conditioner compressor and reservoir/receiver (or desic‐

cancartridge) ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual).

Possible deviation from specification during pressure tes

♦ The requisite cooling outpuis noreached.

♦ High pressure does noincrease or only marginally above the pressure with the engine stationary

♦ The low pressure does nodrop or only marginally

Possible causes for deviation from specification and rectification

♦ The air conditioner compressor is nodriven or nodriven athe specified speed

– Check the drive of the air conditioner compressor (via belts or drive unit) ⇒ Heating, air conditioning; Rep.

gr. 87 ; Air conditioner compressor (vehicle-specific workshop manual).

♦ Actuation of the air conditioner compressor regulating valve - N280- (the air conditioning system magnetic

clutch - N25- ) is defective.

– Check actuation of the air conditioner compressor regulating valve - N280- (and the air conditioning system

magnetic clutch - N25- ) and repair if necessary ⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode

- air conditioning system.

♦ Air conditioner compressor regulating valve - N280- or air conditioner compressor defective

– Check function of -N280- ; if necessary remove -N280- and check for dir⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode - air conditioning system and ⇒ page 79

– -N280- or renew the air conditioner compressor ⇒ page 79

– If diris found in the refrigerancircuit, clean the refrigerancircui(flush with R1234yf refrigerant) and renew

the expansion valve and desiccanbag/desiccancartridge (or renew the receiver/reservoir) ⇒ page 79 ,

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop manual) and

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

♦ Bottle-neck or blockage in refrigerancircui(e.g. in refrigeranline between service connection on “low

pressure side” and air conditioner compressor).

– Touch the refrigerancircuiby hand to feel for a drop in temperature ⇒ Heating, air conditioning; Rep. gr.

87 ; Refrigerancircui(vehicle-specific workshop manual). If a drop in temperature is felon a component,

if there is a kink or bottle-neck in the hose or pipeline, renew this component. In the evenof a blockage or

if no faulcan be found, clean the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92

– Renew the expansion valve and desiccanbag/desiccancartridge (or reservoir/receiver) ⇒ page 79 and

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop manual).

Final measures

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Possible deviation from specification during pressure tes

– Recharge the refrigerancircui⇒ “2.6 Charging refrigerancircuit”, page 146

– Repeat the tes

⇒ “2.14.4 Checking pressures with air conditioning system switched on - vehicles with mechanical air

conditioning compressor”, page 183

Note

♦ If this problem is encountered, ensure thathe air conditioner

compressor (air conditioner compressor shaft) is actually be‐

ing driven via the pulley / drive uni(take note of overload

safety device) ⇒ Heating, air conditioning; Rep. gr. 87 ; Re‐

frigerancircui(vehicle-specific workshop manual).

♦ On certain engines, air conditioner compressors are used tha

feature in addition to -N280- an air conditioning system mag‐

netic clutch - N25- on the belpulley. In the evenof this

problem, make sure tha-N25- is actually being actuated and

thathe air conditioner compressor (air conditioner compres‐

sor shaft) is being driven by the pulley ⇒ Heating, air condi‐

tioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual) and ⇒ Electronic parts catalogue .

♦ If no faulcan be found for this complaint, clean the refrigeran

circui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

lk

♦ Check the measured values of the evaporator outputemper‐

ature sender - G263- and actuation of -N280- . If the measured

value of -G263- is faulty, the evaporator could ice up or the

cooling outpumay nobe reached ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system.

♦ If, after repeating the teswhen the expansion valve has been

renewed, the air conditioning system is nooperating correctly,

clean the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 . Then renew the

air conditioner compressor and reservoir/receiver (or desic‐

cancartridge) ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual).

♦ If the expansion valve is defective (always closed or noopen‐

ing wide enough), -N280- will change to maximum power and

the low pressure will fall to the diagram value or less (the air

conditioner compressor is drawing the refrigeranouof the

low pressure side) ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system. However, since no

refrigerancan flow through the expansion valve, the required

cooling outpuis noreached, the high pressure may also no

rise or only marginally since no energy exchange is taking

place.

Possible deviation from specification during pressure tes

♦ The requisite cooling outpuis noreached.

♦ The high pressure increases beyond the specified value

♦ Low pressure drops quickly to the specification or lower.

Possible causes for deviation from specification and rectification

2. Working with air conditioner service station

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Possible deviation from specification during pressure tes

♦ Actuation of the air conditioner compressor regulating valve - N280- is defective.

– Check the actuation of -N280- and, if necessary, repair ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

mode - air conditioning system.

♦ Constriction or obstruction in refrigerancircui

♦ Expansion valve defective

♦ If a shut-off valve is installed in the refrigerancircuiand idoes noopen correctly or aall ⇒ Heating, air

conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop manual).

– If fitted, check the function of the installed shut-off valve ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐

erancircui(vehicle-specific workshop manual).

– Touch the refrigerancircuiby hand to feel for a drop in temperature ⇒ Heating, air conditioning; Rep. gr.

87 ; Refrigerancircui(vehicle-specific workshop manual). If a drop in temperature is felon a component,

if there is a kink or bottle-neck in the hose or pipeline, renew this component. In the evenof a blockage or

if no faulcan be found, clean the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92

– Renew the expansion valve and desiccanbag/desiccancartridge (or reservoir/receiver) ⇒ page 79 and

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific workshop manual).

Final measures

lk

– Recharge the refrigerancircui⇒ “2.6 Charging refrigerancircuit”, page 146

– Repeat the tes

⇒ “2.14.4 Checking pressures with air conditioning system switched on - vehicles with mechanical air

conditioning compressor”, page 183

Note

♦ In this case, the evaporator may ice up even though the correc

volume of refrigeranis presenin the refrigerancircuit.

♦ If the expansion valve is defective (always closed or noopen‐

ing wide enough) the air conditioner compressor regulating

valve - N280- will be seto maximum power and the low pres‐

sure value will fall to the diagram value or less (the air condi‐

tioner compressor extracts refrigeranfrom the low pressure

side). Since no refrigerancan flow through the expansion

valve, however, the cooling outpuis noreached and the high

pressure may also noincrease or only increase slightly owing

to there being no energy exchange ⇒ Vehicle diagnostic tester

in “Guided FaulFinding” mode - air conditioning system and

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

♦ If there is too much refrigeranin the refrigerancircuit, the air

conditioner compressor musbe emptied and the desiccan

bag (desiccancartridge) or reservoir/receiver renewed. After

cleaning (flushing with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 the refrigerancir‐

cuit, pour the correcvolume of refrigeranoil in the refrigeran

circui⇒ Heating, air conditioning; Rep. gr. 00 ; Technical

data; Approved refrigeranoils and refrigeranoil fill volumes

(vehicle-specific workshop manual) and ⇒ Heating, air con‐

ditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual).

♦ If the specification is noreached again when the tesis re‐

peated buno faulcan be found in the refrigerancircuit, clean

the refrigerancircui(flush with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

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Rep. gr.87 - Air conditioning system

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Possible deviation from specification during pressure tes

♦ The requisite cooling outpuis reached initially buafter a while or after an extended period, the cooling

outpuis no longer sufficient.

♦ The high pressure and the low pressure are normal to starwith

♦ After some time, the high pressure rises above the specification, the low pressure still equates to the

specification or idrops below the specification.

Possible causes for deviation from specification and rectification

♦ Radiator, condenser contaminated or actuation of the radiator is noOK

– Check actuation of the radiator fan and repair if necessary ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system.

– Check condenser for contamination and clean if necessary ⇒ Heating, air conditioning; Rep. gr. 87 ;

Refrigerancircui(vehicle-specific workshop manual) and ⇒ Engine, mechanicals; Rep. gr. 19 ; Radiator/

radiator fan .

♦ Actuation of the air conditioner compressor regulating valve - N280- is defective.

– Check actuation of -N280- and the measured value of evaporator outputemperature sender - G263- ,

repair if necessary ⇒ Vehicle diagnostic tester in “Guided FaulFinding” mode - air conditioning system.

♦ Too much refrigeranin the refrigerancircui

– Extract refrigeranfrom the refrigerancircui⇒ “2.4 Emptying refrigerancircuit”, page 137 .

– If the extracted refrigeranvolume is considerably greater (more than 100 g) than the prescribed fill volume

⇒ Heating, air conditioning; Rep. gr. 00 ; Technical data (vehicle-specific workshop manual), there was

too much refrigeranin the refrigerancircuiRefill the refrigerancircuiwith the correcvolume of R1234yf

and repeathe test.

♦ Air conditioner compressor regulating valve - N280- or air conditioner compressor defective

– Check function of -N280- ; if necessary remove -N280- and check for dir⇒ Vehicle diagnostic tester in

“Guided FaulFinding” mode - air conditioning system and ⇒ “1.5 Renewing components”, page 79

– -N280- or renew the air conditioner compressor ⇒ “1.5 Renewing components”, page 79

– If diris found in the refrigerancircuit, clean the refrigerancircui(flush with R1234yf refrigerant) and renew

the expansion valve and desiccanbag/desiccancartridge (or renew the receiver/reservoir)

⇒ “1.5 Renewing components”, page 79 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

lk

(vehicle-specific workshop manual) and ⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

♦ Too much refrigeranoil in the refrigerancircui

♦ Moisture in refrigerancircui

– Extract refrigeranfrom the refrigerancircui⇒ “2.4 Emptying refrigerancircuit”, page 137 .

– If the extracted refrigeranvolume equates to the prescribed fill volume or is marginally lower (max. 100 g)

⇒ Heating, air conditioning; Rep. gr. 00 ; Technical data (vehicle-specific workshop manual), there is too

much refrigeranoil in the refrigerancircui

– Clean refrigerancircui(flush with R1234yf refrigerant) ⇒ “1.6 Cleaning refrigerancircuit”, page 92 .

– Renew the expansion valve and desiccanbag/desiccancartridge (or reservoir/receiver)

⇒ “1.5 Renewing components”, page 79 and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerancircui

(vehicle-specific workshop manual).

Final measures

– Recharge the refrigerancircui⇒ “2.6 Charging refrigerancircuit”, page 146

– Repeat the tes

⇒ “2.14.4 Checking pressures with air conditioning system switched on - vehicles with mechanical air

conditioning compressor”, page 183

2. Working with air conditioner service station

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Note

♦ If there is too much refrigeranin the refrigerancircuit, the air

conditioner compressor musbe emptied and the desiccan

bag (desiccancartridge) or reservoir/receiver renewed. After

cleaning (flushing with R1234yf refrigerant)

⇒ “1.6 Cleaning refrigerancircuit”, page 92 the refrigerancir‐

cuit, pour the correcvolume of refrigeranoil in the refrigeran

circui⇒ Heating, air conditioning; Rep. gr. 00 ; Technical

data; Approved refrigeranoils and refrigeranoil fill volumes

(vehicle-specific workshop manual) and ⇒ Heating, air con‐

ditioning; Rep. gr. 87 ; Refrigerancircui(vehicle-specific

workshop manual).

♦ In this case, the evaporator may ice up even though the correc

volume of refrigeranis presenin the refrigerancircuit.

♦ A faulin the evaporator outputemperature sender - G263-

could also cause the refrigerancircuito ice up. With this

complaint, also observe the measured value of -G263- ⇒ Ve‐

hicle diagnostic tester in “Guided FaulFinding” mode - air

conditioning system and ⇒ Heating, air conditioning; Rep. gr.

87 ; Overview of fitting locations - air conditioning system (ve‐

hicle-specific workshop manual).

lk

Possible deviation from specification during pressure tes

♦ The requisite cooling outpuis reached initially buafter a shoror extended period, the required level is no

longer reached.

♦ The high pressure and low pressure are normal to starwith buafter a while, the high pressure rises above

the specification and the low pressure drops to the specification or lower.

♦ The high pressure and low pressure are normal to starwith. After a while, the low pressure drops to the

specification or lower and the evaporator ices up.

Possible causes for deviation from specification and rectification

198

Rep. gr.87 - Air conditioning system

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Air conditioning systems with refrigeranR1234yf - General information - Edition 07.2017

Possible deviation from specification during pressure tes

♦ Radiator, condenser contaminated or actuation of the radiator is noOK

– Check actuation of the radiator fan and repair if necessary ⇒ Vehicle diagnostic tester in “Guided Faul

Finding” mode - air conditioning system.

– Check condenser for contamination and clean if necessary ⇒ Heating, air conditioning; Rep. gr. 87 ;

lk

Refrigerancircui(vehicle-specific workshop manual) and ⇒ Engine, mechanicals; Rep. gr. 19 ; Radiator/

radiator fan .

♦ Measured value of evaporator outputemperature sender - G263- faulty.

– Check measured value and installation of -G263- ⇒ Vehicle diagnostic tester in “Guided FaulFinding”

function - air conditioning system and ⇒ Heating, air conditioning; Rep. gr. 87 ; Overview of fitting locations

- air conditioning system .