Get Air conditioning system -> 1.6.4 Principle circuit diagrams for cleaning (flushing circuits) - refrigerant circuit with expansion valve and receiver 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

All vehicles

Note

♦ VW/Volkswagen/Audi does not endorse the use of chemical

substances (leak inhibitor additives) for purposes of sealing

leaks in refrigerant circuits.

♦ These chemical substances (leak stop additives) react mostly

with the ambient air or the humidity to stop leaks in the refrig‐

erant circuit. They cause deposits to build up in the refrigerant

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

to malfunction and defects in other components with which

they come into contact. These deposits cannot be completely

removed from the components again (not even by flushing).

The refrigerant circuit can only be repaired by replacing all

components that have come into contact with this substance.

♦ There are often no external signs to suggest that chemical

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

in a refrigerant circuit. Often, the stickers provided to mark

such systems are missing. Therefore, exercise caution on ve‐

hicles for which you have no service or repair record.

♦ If there is no suitable air conditioner service station available

for the R1234yf refrigerant, the air conditioner service station

designed for R134a refrigerant may also be used and the re‐

frigerant circuit may also be flushed with R134a refrigerant.

Using R134a refrigerant to clean the refrigerant circuit is cur‐

rently permissible ⇒ Air conditioning system with R134a re‐

frigerant; Rep. gr. 87 ; General information about the air

conditioning system and refrigerant circuit .

♦ If during the gas analysis it is found that R1234yf refrigerant

has been contaminated with a different gas, it must be extrac‐

ted from the refrigerant circuit and disposed of as a gas of

unknown composition in accordance with the relevant legisla‐

tion ⇒ VW / Audi-ServiceNet and

⇒ “2.13 Filling contaminated refrigerant in a recycling cylinder

for analysis, processing or disposal”, page 161 .

♦ Contaminated refrigerant can cause decomposition products

to form and accumulate in the refrigerant circuit. These cannot

be extracted with the refrigerant. The contaminated refrigerant

oil, in this case, must be removed from the refrigerant circuit

by flushing with refrigerant.

•

To work as cleanly as possible, without being wasteful of the

refrigerant, without complex assembly work and in an envi‐

ronmentally friendly manner when removing moisture, con‐

taminants (e.g. friction dust and particles from the defective air

conditioner compressor) and old refrigerant oil, the refrigerant

circuit must be flushed (using R1234yf refrigerant).

The refrigerant circuit must be cleaned (flushed) with refrigerant

R1234yf:

– If dirt or other contamination is in the circuit.

– The search for faults in the electrical system, the vacuum sys‐

tem and the air ducts did not turn up any fault.(Moisture is in

the refrigerant circuit and builds up pressure.)

– If the refrigerant circuit has been left open for longer than nor‐

mally required for repairs (e.g. following an accident).

– Pressure and temperature measurements in the circuit indi‐

cate that there is moisture in the refrigerant circuit.

– There is doubt about the amount of refrigerant oil in the refrig‐

erant circuit.

1. Refrigerant circuit

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

– Under certain circumstances if contaminated R1234yf refrig‐

erant was charged in the refrigerant circuit

⇒ “1.5 Renewing components”, page 79 and

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

Note

If contaminated refrigerant is found and components of the re‐

frigerant circuit exhibit signs of internal damage (e.g. corrosion on

the inside of the refrigerant lines or breakdown of the inner layer

of refrigerant hoses), flushing the refrigerant circuit may not be

sufficient. In this case, all of the components of the refrigerant

circuit must be renewed (owing to a gas being charged that se‐

verely damaged the components).

– The air conditioner compressor has to be exchanged because

of internal damage (e.g. noisy or lack of power)

⇒ “1.5 Renewing components”, page 79 .

– If it is required by the workshop manual for the specific vehicle

following the renewal of certain components.

Tools required

♦ Air conditioner service station with flushing device (this air

conditioner service station incorporates the auxiliary function

“flushing refrigerant circuit” and the corresponding flushing

device for refrigerant circuits ⇒ Electronic parts catalogue .

♦ Adapter case for Volkswagen/Audi passenger vehicles

⇒ page 105 and ⇒ Electronic parts catalogue .

Note

♦ If you do not have an air conditioner service station with flush‐

ing device ⇒ Electronic parts catalogue in your workshop, it

may be possible depending on the version of your air condi‐

tioner service station to use the refrigerant circuit flushing

device ⇒ Electronic parts catalogue to flush the refrigerant

circuit. However, the flushing routine must be performed man‐

ually ⇒ page 159 .

♦ In adapter case passenger vehicle set there is also a filling

hose with 5/8 -18 UNF connections and large inner diameter,

short type (commercially available).

1.6.2

Preparations for cleaning refrigerant cir‐

cuit (flushing with R1234yf refrigerant)

– Drain refrigerant circuit

⇒ “2.4 Emptying refrigerant circuit”, page 137 .

– Remove air conditioner compressor ⇒ Heating, air condition‐

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

refrigerant circuit (vehicle-specific workshop manual).

On vehicles with restrictor and reservoir

– Remove restrictor (vehicle-specific) and join the lines together

again ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant

circuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

– Remove the reservoir (vehicle-specific) and join the lines to‐

gether again (using an adapter and the charging hose from the

adapter case for VW/Audi passenger vehicles )

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

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

Rep. gr.87 - Air conditioning system

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

cuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

Note

The reservoir could be flushed. However, due to its large interior

volume it draws too much refrigerant and when this is extracted,

the reservoir ices up too heavily. This causes the refrigerant to

evaporate only very slowly, lengthening the extraction process

too much as a result.

On vehicles with expansion valve and receiver

– If possible and necessary with this refrigerant circuit (see no‐

tice), remove the receiver or remove the desiccant cartridge

from the receiver (vehicle-specific) and join the lines together

again (using an adapter and the charge hose from the adapter

case for Volkswagen/Audi passenger vehicles )

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

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

cuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

Note

♦ Depending on the design, the receiver can be flushed (if nec‐

essary, remove dryer cartridge installed in receiver)

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

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

cuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

♦ If the receiver is attached to the condenser, it must not be re‐

moved for flushing (its design makes it suitable for flushing,

and it is only renewed after flushing)

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

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

cuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

♦ With condensers in which the receiver / desiccant cartridge are

integrated and cannot be renewed individually or are not avail‐

able as individual parts, the condenser is to be renewed after

flushing. On these vehicles, the condenser in this case is to

be renewed with the receiver ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerant circuit; System overview - refrigerant cir‐

cuit (vehicle-specific workshop manual) and ⇒ Electronic

parts catalogue .

♦ Depending on the version, receivers - in which the desiccant

cartridge is to be renewed individually - may feature an addi‐

tional filter element, which will need to be renewed with the

desiccant cartridge if necessary.

– On vehicles with a dryer cartridge in the receiver on the con‐

denser (vehicle-specific), remove the dryer cartridge and seal

the opening on the receiver again ⇒ Heating, air conditioning;

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

circuit (vehicle-specific workshop manual).

– Remove expansion valve (vehicle-specific) and fit an adapter

from the adapter case for Volkswagen/Audi passenger vehi‐

cles in its place

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

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

cuit; System overview - refrigerant circuit (vehicle-specific

workshop manual).

1. Refrigerant circuit

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

Note

If there is not a suitable adapter for the expansion valve in the

adapter case Volkswagen/Audi passenger vehicle set , the re‐

moved expansion valve can also be drilled out (the old expansion

valve has to be replaced in most cases anyway and is no longer

required).

– The sealing surfaces of the expansion valve must not be dam‐

aged. If damage is caused to the sealing surfaces, refrigerant

could escape.

– Drill out expansion valve.

Note

♦ Before drilling, remove the regulator element and drill out the

expansion valve using e.g. a suitably sized drill bit (diameter

of drill bit e.g. 6.0 mm).

♦ Before drilling out, some parts may have to be removed from

the expansion valve depending on the version.

♦ There are different types of expansion valve with different de‐

signs. For type -A-, parts -B-, -C- and -D- must be removed,

for example. Separate component -D- and then part -E- (the

regulating element). Then drill out the expansion valve in area

-F- using a suitably sized drill bit.

♦ On version -G-, parts -H-, -I- and -K-, for example, must be

removed and then area -L- drilled out using a suitably sized

drill bit.

– Clean the drilled out expansion valve of swarf (metal particles).

– Reinstall parts -B-, -C- and -D- on type -A- or part -H- on type

-G-.

Note

On vehicles with 2 evaporators, separate the circuit to the second

evaporator from the circuit of the first evaporator and flush it in a

separate work step

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

⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit; Sys‐

tem overview - refrigerant circuit (vehicle-specific workshop man‐

ual).

♦ Clean (flush) the refrigerant circuit

⇒ “2.12 Cleaning refrigerant circuit”, page 157

1.6.3

Refrigerant circuit cleaning procedure

Note

The procedure runs automatically as per the program in the air

conditioner service station ⇒ Operating instructions air condi‐

tioner service station .

♦ After switching on, the flushing circuit (refrigerant circuit with

connecting hoses and flushing device for refrigerant circuits)

is evacuated first and, in the process, the refrigerant circuit is

checked for leaks (it may be necessary to proceed to the next

Rep. gr.87 - Air conditioning system

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

step manually depending on the version of air conditioning

service station ).

♦ Once the refrigerant circuit has been checked for leaks by

means of evacuating, a certain amount of refrigerant is filled

in the system to check the flushing/refrigerant circuit for correct

assembly (pressure test).

♦ After the pressure test, the refrigerant is extracted, the refrig‐

erant circuit is evacuated again, if necessary, and the cleaning

(flushing) process begins.

♦ A predefined volume of refrigerant is charged in the refrigerant

circuit via the high pressure side of the air conditioner service

station (in the opposite direction of normal flow during air con‐

ditioning system operation and therefore on the low pressure

side of the vehicle's refrigerant circuit). Alternatively, refriger‐

ant is charged continually (depending on the internal volume

of the flushing circuit e.g. 3 kg) until the refrigerant circuit and

the inspection windows of the flushing device for refrigerant

circuits are completely full with liquid refrigerant (the system

detects, e.g. over a certain period of time, when refrigerant

ceases to flow depending on the version of air conditioner

service station ).

♦ Once the predetermined amount of refrigerant has been filled

in the system, the heater, for example, of the flushing device

for refrigerant circuits is switched on depending on the type of

air conditioner service station and flushing device for refriger‐

ant circuits (only if the refrigerant is extracted in gaseous form

out of the flushing device for refrigerant circuits).

♦ When the refrigerant has been extracted, the heater of the

flushing device for refrigerant circuits is switched off (if fitted),

the refrigerant circuit may have to be evacuated briefly again

depending on the type, and following evacuation the refriger‐

ant oil evacuated by the air conditioner service station out of

the refrigerant circuit is separated of water.

♦ The procedure for charging with refrigerant, extracting (and

evacuating) is carried out three times (that means a total of

four times).

♦ After extracting for the fourth time, the flushing circuit is evac‐

uated depending on the type of air conditioner service station .

1.6.4

Principle circuit diagrams for cleaning

(flushing circuits) - refrigerant circuit with

expansion valve and receiver

♦ With 1 or 2 evaporators

♦ With and without high-voltage system

1. Refrigerant circuit

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

Note

♦ The arrows in the following illustrations show the direction of

refrigerant flow during flushing (during flushing, the refrigerant

flows against the direction of flow with normal air conditioning

operation, which is why the high pressure side of the air con‐

ditioner service station is connected on the low pressure con‐

nection of the refrigerant circuit to the air conditioner

compressor).

♦ This principle circuit diagram shows a refrigerant circuit with

expansion valve, receiver and a second evaporator (extra

equipment on certain vehicles).

♦ On vehicles with expansion valve and receiver, the expansion

valve is removed and an adapter installed in its place. The

receiver is also removed depending on the vehicle and the line

connections to the receiver are joined together with 2 adapters

and a filling hose.

♦ On vehicles with just one evaporator, the components from

position “16” are not installed or not required.

♦ Depending on the design of the air conditioner service station

there may be non-return valves installed between the refrig‐

erant circuit and the air conditioner service station (to assure

the correct direction of refrigerant flow during flushing).

♦ The adapters from the adapter case for VW/Audi passenger

vehicles have a 5/8 -18 UNF thread. To ensure that the charge

hoses of the R1234yf- air conditioner service station can be

connected, additional adapters from the case are to be used

adapter case for VW/Audi passenger vehicles ⇒ Electronic

parts catalogue .

♦ Installed in the refrigerant circuit on vehicles with a high-volt‐

age system are electrically actuated valves that have to be

removed for cleaning (flushing) and replaced with manual

shut-off valves or adapters ⇒ Heating, air conditioning; Rep.

gr. 87 ; Refrigerant circuit .

Rep. gr.87 - Air conditioning system

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Air conditioning system -> 1.6.4 Principle circuit diagrams for cleaning (flushing circuits) - refrigerant circuit with expansion valve and receiver for Your Volkswagen Touran 4 Door Second Generation (2015-2022)

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