Get Air conditioning system -> 2.5 Evacuating refrigerant circuit Guide for Volkswagen Touran 4 Door Second Generation (2015-2022)

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

components of the refrigerant circuit (e.g. the condition of the

internal surfaces of removed refrigerant lines and refrigerant

hoses, the internal surface of the refrigerant reservoir and the

condition of the removed dryer cartridge).

♦ If internal damage has been caused to the refrigerant circuit

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

tioner compressor has ensued owing to damaged control

elements or overheating, refrigerant oil has a stronger colour

than usual but the parts containing refrigerant have not been

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

erant circuit can be charged again once it has been flushed

(renew air conditioner compressor, dryer and expansion

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

term effect of the contaminated refrigerant on the refrigerant

oil and the components of the refrigerant circuit, no guarantee

can be given in this case that the components of the refrigerant

circuit will function correctly in future.

♦ If the contaminated refrigerant has not caused internal dam‐

age to the refrigerant circuit (e.g. the refrigerant oil does not

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

frigerant circuit have not been affected), the refrigerant circuit

can be charged again once the dryer has been renewed and

the refrigerant circuit has been evacuated for an extended pe‐

riod (at least 1 hour). However, since there is no way of

anticipating the long-term effect of the contaminated refriger‐

ant on the refrigerant oil and the components of the refrigerant

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

ponents of the refrigerant circuit will function correctly in future

⇒ “1.5 Renewing components”, page 79 .

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

Note

♦ If there is a complaint that can be attributed to the contamina‐

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

conditioner compressor, contaminated refrigerant oil), the re‐

frigerant circuit must be flushed and then all components that

were damaged by the contaminated refrigerant (seals, hoses,

reservoir or dryer cartridge, expansion valve and air condi‐

tioner compressor) must be renewed. If it is found that the

contaminated refrigerant has affected other components as

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

frigerant hoses, damaged seals), the complete refrigerant cir‐

cuit must be renewed. The refrigerant circuit must then be

recharged with clean refrigerant. Then check the function of

the air conditioning system. For the customer and to safeguard

yourself, make a note that the refrigerant circuit was charged

with contaminated refrigerant.

♦ If there is a complaint that can be attributed to the contamina‐

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

complaints can be found in the refrigerant circuit, or if the re‐

frigerant has to be extracted because work in the area of the

refrigerant circuit so requires, proceed as follows after evacu‐

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

nation. Since there could also be refrigerant oil on or in the

dryer, check this as well. If the refrigerant oil is contaminated,

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

flush the refrigerant circuit and 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‐

frigerant oil is OK and the dryer is not contaminated any more

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

ate the refrigerant circuit for an extended period (at least 1

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 that the refrigerant circuit

was charged with contaminated refrigerant.

2.4

Emptying refrigerant circuit

•

Depending on the type of equipment chosen, there may be

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

equipment being used) ⇒ Operating instructions air condi‐

tioner service station .

•

The refrigerant circuit should be emptied if parts of the refrig‐

erant circuit are to be removed, if it is unclear whether there is

refrigerant in the circuit, if contaminated refrigerant was de‐

termined during the gas analysis, or if safety precautions so

demand.

•

All of the operating instructions for work involving refrigerant

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‐

frigerant circuit that are not open when de-energised:

2. Working with air conditioner service station

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

Note

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

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

voltage battery”), valves may be installed in the refrigerant circuit

that are not open 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

correct evacuation and charging of the refrigerant circuit, howev‐

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

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

Rep. gr. 87 ; Refrigerant circuit; System overview - refrigerant

circuit and ⇒ Vehicle diagnostic tester in “Guided Fault Finding”

mode.

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

not open 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

refrigerant circuit (see vehicle-specific refrigerant circuit) ⇒

Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit;

System overview - refrigerant circuit .

– Connect air conditioner service station to refrigerant circuit

⇒ “2.2 Connecting air conditioner service station to refrigerant

circuit”, page 131 .

– Perform a gas analysis with the air conditioner service station

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

Note

♦ If during the gas analysis it is found that the R1234y refrigerant

is contaminated, extract the refrigerant from the refrigerant

circuit and send it e.g. back to your gas supplier for analysis,

processing or disposal

⇒ “6.2.17 Returning contaminated R1234yf refrigerant for

analysis, processing or disposal”, page 25 .

♦ Refill the refrigerant that is contaminated into a recycling cyl‐

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

cessing or disposal

⇒ “6.2.17 Returning contaminated R1234yf refrigerant for

analysis, processing or disposal”, page 25 .

– Evacuate the refrigerant circuit with the air conditioner service

station as instructed in the associated operating manual.

NOTICE

Risk of damage to air conditioner compressor if refrigerant cir‐

cuit is empty.

– Never start the engine if the refrigerant circuit is empty.

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Note

♦ Sometimes, refrigerant oil is extracted from the refrigerant cir‐

cuit along with the refrigerant and there is no way of stopping

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

compressor, the refrigerant oil quantity should be topped up

with fresh refrigerant oil

⇒ “2.6 Charging refrigerant circuit”, page 146 .

♦ Where vehicles are fitted with an air conditioner compressor

without a magnetic clutch (with air conditioner compressor

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

refrigerant circuit empty for no longer than is absolutely nec‐

essary, making sure that higher engine speeds are avoided

(since the air conditioner compressor will always run when the

engine is running).

♦ On vehicles that have an air c^lo^knditioner compressor without

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

pletely assembled refrigerant circuit, ensuring that higher en‐

gine speeds are avoided.

♦ Depending on the version of air conditioner compressor, a

valve may be installed on the high-pressure side that prevents

liquefied refrigerant flowing 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 refrigerant circuit with expansion valve, it could

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 refrigerant only flows slowly on the low-

pressure side). If the air conditioner compressor is switched

on (or the refrigerant circuit is emptied via the low pressure

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

valve opens and refrigerant can flow on the low pressure side.

If it is necessary after emptying to perform work on the vehicle for

which the air conditioner service station is not required:

– Detach the air conditioner service station from the refrigerant

circuit and switch off

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

rating from refrigerant circuit”, page 151 .

– Open the refrigerant circuit at a 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 refrigerant and open the refrigerant circuit immedi‐

ately afterwards.

– If more than 10 minutes have passed since the refrigerant

was extracted, repeat the extraction process before opening

the refrigerant circuit. Pressure could build up in the refrig‐

erant circuit from continued evaporation.

– Perform the required measures on the refrigerant circuit.

If, after emptying, the refrigerant circuit is to be evacuated and

recharged ⇒ “2.5 Evacuating refrigerant circuit”, page 140 .

2. Working with air conditioner service station

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

Note

♦ After opening the connecting points in the refrigerant circuit,

the open lines and component connections must be closed (so

that the ingress of moisture and dirt in these components is

prevented).

♦ Sometimes, refrigerant oil is extracted from the refrigerant cir‐

cuit along with the refrigerant and there is no way of stopping

this. To ensure lubrication of the air conditioner compressor,

the refrigerant oil quantity should be topped up with fresh oil.

♦ Where vehicles are fitted with an air conditioner compressor

with air conditioner compressor regulating valve - N280- , the

engine should be run with the refrigerant circuit empty for no

longer than is absolutely necessary, making sure that higher

engine speeds are avoided (since the air conditioner com‐

pressor will always run when the engine is running).

♦ On vehicles that have an air conditioner compressor with air

conditioner compressor regulating valve - N280- , the engine

may only be started with a completely assembled refrigerant

circuit, ensuring that higher engine speeds are avoided.

2.5

Evacuating refrigerant circuit

•

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 refrigerant oil volume in the air conditioner service station

has been checked and, if necessary, adjusted ⇒ Operating

instructions of air conditioner service station .

The refrigerant volume in the air conditioner service station

has been checked and, if necessary, adjusted ⇒ Operating

manual of air conditioner service station .

Before the refrigerant circuit is filled with refrigerant, it must be

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

ture is drawn out of the circuit.

Leaks can be determined when evacuating the refrigerant circuit

⇒ “1.4 Investigating leaks”, page 68 .

NOTICE

Risk of damage to air conditioner compressor with negative

pressure in the refrigerant circuit.

– Never start the engine if there is negative pressure in the

refrigerant circuit.

Evacuating:

•

The refrigerant circuit is 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‐

frigerant circuit that are not open when de-energised:

140

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

Note

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

tioning system functions (“heat pump mode” or “cooling of

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

ant circuit that are not open 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 refrigerant

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

valves must be opened before work is carried out ⇒ Heating,

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

cific workshop manual) and ⇒ Vehicle diagnostic tester in

“Guided Fault Finding” mode.

♦ Non-return valves in the refrigerant circuit have a certain hold‐

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

100 mbar). To ensure that the refrigerant circuit can be evac‐

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

electrically actuated valves must therefore be open.

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

tuated valves that are not open when de-energised ⇒ Vehicle

diagnostic tester in “Guided Fault Finding” 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

refrigerant circuit (see vehicle-specific refrigerant circuit) ⇒

Heating, air conditioning system; Rep. gr. 87 ; Refrigerant cir‐

cuit (vehicle-specific workshop manual).

– Check service connections of refrigerant circuit for contami‐

nation or corrosion, clean if necessary.

Note

Dirt or 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 refrigerant

circuit

⇒ “2.2 Connecting air conditioner service station to refrigerant

circuit”, page 131 .

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

frigerant circuit and perform the vacuum test (for a period of

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

remains of refrigerant and moisture and 20 minutes for the

vacuum/pressure increase check).

2. Working with air conditioner service station

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Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

Note

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

vacuum pump of air conditioner service station ) must be less

than 5 mbar absolute pressure. Should pressure during the

evacuating process in the refrigerant circuit not be less than

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

the refrigerant circuit or in the connection to the air conditioner

service station , the time for the evacuating process is set too

short, the vacuum pump of the air conditioner_lkservice station

does not generate the necessary vacuum or the vacuum sen‐

sor of the air conditioner service station is not calibrated prop‐

erly ⇒ Operating instructions air conditioner service station .

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

975 mbar at an ambient pressure e.g. of 980 mbar.

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

in the refrigerant circuit should not be greater than 20 mbar

absolute. Should the pressure in the refrigerant circuit be

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 refrigerant

circuit still not be 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 refrigerant circuit, a leak in

the connection from the refrigerant circuit to the air conditioner

service station or in the air conditioner service station itself,

the time set for the evacuating process is too short and the

time set for the vacuum/pressure increase check is too long.

♦ If there is reason to suspect a leak in the refrigerant circuit,

switch off the air conditioner service station if necessary and

allow it to stand for as long as possible (e.g. for at least 1 hour

to check the leak-tightness of the refrigerant circuit) ⇒ Oper‐

ating instructions air conditioner service station .

♦ Depending on the version of air conditioner service station ,

the pressure in the refrigerant circuit is displayed directly.

However, there is also a chance that the current pressure is

only displayed while the vacuum pump is running ⇒ Operating

instructions air conditioner service station . In the event of an

air conditioner service station only displaying the ambient

pressure, the display of the pressure in the refrigerant circuit

will depend on the ambient pressure during activation (ambi‐

ent pressure at 980 mbar, a vacuum of 975 mbar equates to

a residual pressure of 5 mbar absolute).

♦ If the refrigerant circuit was opened, small quantities of mois‐

ture may have entered the refrigerant circuit. In this case, the

refrigerant circuit is to be evacuated for at least 30 minutes

(pressure in the refrigerant circuit before charging must be less

than 20 mbar).

♦ If the refrigerant was extracted (to check the fill volume) and

the refrigerant circuit was only evacuated so that it could be

recharged (the refrigerant circuit was not opened and is leak-

tight), it is sufficient to evacuate the refrigerant circuit for 5

minutes and to set no time or only a short time (e.g. 1 minute)

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

entered the refrigerant circuit).

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Air conditioning system -> 2.5 Evacuating refrigerant circuit for Your Volkswagen Touran 4 Door Second Generation (2015-2022)

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