VW Golf manuals

Volkswagen Golf Service & Repair Manual: Purging (cleaning) refrigerant circuit with refrigerant R134a

Vehicles with high-voltage system (hybrid vehicles)
Observe the additional warning instructions for working on vehicles with high-voltage system → Electrical system; Rep. gr.93.
  WARNING
Risk of injury due to unexpected engine start
When working on a high-voltage vehicle, switch off the ignition, and deposit the ignition key somewhere outside the passenger compartment.
  WARNING
Handling high-voltage cables:
Do not support yourself or your tools on high-voltage cables and their components --> risk of damage to the insulation.
High-voltage cables must not be extensively bent or kinked --> risk of damage to the insulation.
The round high-voltage connectors are colour-coded with a coloured ring on the outside and mechanically coded with respective guide lugs. Always observe the coding when connecting the round high-voltage connectors in order to prevent any mechanical damage to the high-voltage connectors.
  DANGER!
Hazardous voltage resulting from damaged high-voltage components
Observe the following when working in the vicinity of high-voltage components and cables:
Work involving metal-removing, deforming and sharp-edged tools or heat sources such as welding, soldering, hot air and thermal bonding is not permitted.
Before starting work, carry out a visual check on the high-voltage components in the area of work.
When working in the engine compartment, carry out a visual check on the power and control electronics for electric drive -JX1-, the electric drive motor -V141-, the air conditioner compressor -V470- and the high-voltage cables.
When working on the underbody, carry out a visual check on the high-voltage cables and covers.
When working on the rear end, carry out a visual check on the high-voltage cables and the maintenance connector for high-voltage system - TW -.
Carry out a visual check on all potential equalisation lines.
When carrying out the visual check, observe the following:
The high-voltage components must not reveal any external damage.
The insulation of the high-voltage cables and the potential equalisation lines must not be damaged.
The high-voltage cables must not show any unusual deformations.
Each high-voltage component must be clearly identified with a red warning sticker.
If repair work in the vicinity of high-voltage components and cables is necessary, “carry out a visual check for damage on high-voltage components and cables”, and “observe the general warning instructions for work on the high-voltage system” → Electrical system; Rep. gr.93.
If repair work on high-voltage components is necessary, de-energise the high-voltage system → Electrical system; Rep. gr.93, and “observe the general warning instructions for work on the high-voltage system” → Electrical system; Rep. gr.93.
  Caution
If there is evidence to suggest that chemical substances have been added in the vehicle to seal leaks, do not connect the air conditioner service station and do not extract the refrigerant.
Chemical substances used to seal leaks form deposits in the refrigerant circuit. These can impair the function of the air conditioning system and cause the air conditioning system (and your air conditioner service station) to fail.
Make your customer aware of the fact that there are substances in his/her air conditioning system that do not have VW approval and therefore the refrigerant circuit cannot be purged. The refrigerant circuit can only be repaired by replacing all components that have come into contact with this substance. .
  Note
Volkswagen rejects the use of chemical substances for purposes of sealing leaks in refrigerant circuits.
Chemical substances used for sealing leaks in refrigerant circuits often react with the surrounding air and the humidity contained within. They cause deposits to build up in the refrigerant circuit (and your air conditioner service station), valves to malfunction and defects in other components with which they come into contact. These deposits cannot be completely removed from the components (not even by purging). The refrigerant circuit can only be repaired by replacing all components that have come into contact with this substance.
It is often not possible to detect from the outside whether chemical substances have been used to seal leaks in the refrigerant circuit. The adhesive label that serves to identify its use can usually not be found. Therefore, exercise caution on vehicles for which you have no service or repair record.
To work as cleanly as possible and avoid the task becoming labour intensive when removing contaminants (e.g. friction dust and particles from defective air conditioner compressor) and old refrigerant oil, the refrigerant circuit must be purged using refrigerant R134a.
On vehicles with electrical air conditioner compressor, observe the notes on renewing the electrical air conditioner compressor -V470-. If the electronics of the air conditioner compressor are damaged, the refrigerant circuit does not always need to be cleaned. → Chapter
The refrigerant circuit must be purged with refrigerant R134a if:
Dirt or other contaminants are in the refrigerant circuit.
If during evacuation of a leak-tight refrigerant circuit the vacuum display is not constant on gauge (moisture in the refrigerant circuit, which generates vapour pressure).
If the refrigerant circuit has been left open for longer than normally required for repairs (e.g. following an accident).
Pressure and temperature measurements in the refrigerant circuit indicate that there is moisture in the refrigerant circuit.
There is doubt about the amount of refrigerant oil in the refrigerant circuit. If the air conditioner compressor is to be reinstalled, drain refrigerant oil out of air conditioner compressor via the drain plug. To facilitate this process, turn the air conditioner compressor over by hand at the poly V-belt pulley or coupling disc of the magnetic coupling. After purging, fill refrigerant circuit with total amount of refrigerant oil (50 g direct into air conditioner compressor) according to → vehicle-specific workshop manual. Observe additional oil requirements for systems with second evaporator.
The air conditioner compressor has to be exchanged because of internal damage (e.g. noisy or no output).
the vehicle-specific repair manual deems it necessary after replacement of certain components.
a different air conditioner compressor with other refrigerant oil is to be fitted.
Tools required
Air conditioner service station with purging device -VAS 6381- or air conditioner service station with purging device -VAS 6337-. These air conditioner service stations feature an additional function for “purging the refrigerant circuit with R134a” and the purging device for refrigerant circuits necessary for this procedure → Workshop equipment and special tools catalogue.
Adapter case VW/Audi passenger vehicle set -VAS 6338/1- → Chapter and → Workshop equipment and special tools catalogue.
Adapter case commercial vehicle set -VAS 6338/50- → Chapter and → Workshop equipment and special tools catalogue.
  Note
If the above mentioned air conditioner service stations are not available in the workshop, the rinsing device for refrigerant circuits -VAS 6336/1- or rinsing device for refrigerant circuits -VAS 6337/1- can be used to purge the refrigerant circuit, depending on the type of air conditioner service station in service (min. 7 kg refrigerant R134a in refrigerant bottle). The purging process must then be carried out manually → Anchor.
On vehicles with threaded connections on the refrigerant circuit, adapter -V.A.G 1785/1- to adapter -V.A.G 1785/8- from adapter case VW/Audi passenger vehicle set -VAS 6338/1- or adapter case commercial vehicle set -VAS 6338/50- can be used. On vehicles with threaded connections on the air conditioner compressor and on the reservoir, the adapter -V.A.G 1785/8- is required two-fold.
In the adapter case there is also a charging hose -VAS 6338/31- with 5/8 - 18 UNF connections and large internal diameter to bridge components (commercially available type).
Preliminary measures
–  Drain refrigerant circuit → Chapter.
–  Remove air conditioner compressor → Heating, air conditioning.
On vehicles with restrictor and reservoir.
–  Remove restrictor (vehicle-specific) and join the refrigerant lines together again → Heating, air conditioning.
–  Remove reservoir (vehicle-specific) → Heating, air conditioning and join refrigerant pipes together again (to do this, use adapter and charging hose -VAS 6338/31- from adapter case VW/Audi passenger vehicle set -VAS 6338/1-) → Chapter.
  Note
The collector could be purged but due to its large inner volume it would require too much refrigerant. During extraction, the refrigerant ices up the reservoir heavily and the extraction procedure takes much longer as a result.
On vehicles with expansion valve and receiver.
–  Remove the receiver → Heating, air conditioning (vehicle-specific, not necessary on all vehicles) and join the refrigerant lines together (use the adapter and the charging hose -VAS 6338/31- to do this) → Chapter.
–  Remove the expansion valve → Heating, air conditioning (vehicle-specific) and insert an adapter in its place → Chapter.
  Note
If there is not a suitable adapter for the expansion valve in the adapter case VW/Audi passenger vehicle set -VAS 6338/1- or adapter case commercial vehicle set -VAS 6338/50-, the removed expansion valve can also be drilled out (the old expansion valve must be subsequently renewed).
  Caution
When drilling out, ensure that the sealing surfaces on the expansion valve are not damaged.
Refrigerant would otherwise escape.
  Note
   
Before drilling out, some parts have to be removed from the expansion valve.
There are two types of expansion valve. For type -A-, parts -B-, -C- and -D- must be removed. Separate regulator -E- from component -D-. Then drill through expansion valve in area -F- using a suitable 6 mm drill.
On version -G-, parts -H-, -I- and -K- must be removed and then area -L- drilled out with a suitably sized drill bit (6 mm in diameter).
Clean away any swarf from the drilled out expansion valve.
Reinstall parts -B-, -C- and -D- on type -A- or part -H- on type -G-.
  Note
On vehicles with two evaporators, the circuit to the second evaporator must be isolated from the circuit to the first evaporator and purged in a separate procedure → Heating, air conditioning and → Chapter.
Drill open shut-off valve.
  Note
Two shut-off valves are required for purging the refrigerant circuit. A shut-off valve must be drilled open, if no shut-off tap -VAS 6338/42- is available, for example.
 

Purging (cleaning) refrigerant circuit with refrigerant R134a

Remove the solenoid -A- and the solenoid valve -B- before drilling open the shut-off valve.
Drill open the shut-off valve -C- using a suitable drill bit (e.g. 5 mm in diameter).
Remove any metal shavings resulting from drilling hole -D- from shut-off valve -C-.
Reinstall the solenoid valve -B- with the respective seal -E- to the shut-off valve -C- which has been drilled open.
Purging
–  Check the refrigerant volume in the air conditioning bottle. There must be at least 7 kg of R134a refrigerant.
  Note
Switch on the heater attached to the refrigerant bottle 30 minutes before the first purging process, if necessary. In this way, pressure in the refrigerant bottle is increased and charging of the purging circuit is accelerated.
–  Drain the waste oil container of the air conditioner service station.
–  Connect the supply hose (high-pressure side) of the air conditioner service station with an adapter → Chapter to the low-pressure line leading to the air conditioner compressor (line with larger diameter).
–  Connect the return hose (low-pressure or suction side) of the air conditioner service station to the outlet of the purging device for refrigerant circuits.
–  Connect the inlet of the purging device for refrigerant circuits with an adapter → Chapter to the high-pressure line leading to the air conditioner compressor (line with smaller diameter).
  Note
The components must always be purged against the direction of refrigerant flow when the air conditioning system is in operation (not applicable for electrical air conditioner compressor) → Chapter.
When purging, contaminants from the refrigerant circuit enter the purging device for refrigerant circuits and the air conditioner service station and are retained in the filters and dryers installed within. Depending on the contaminants, these components must be changed at shorter intervals in accordance with the operating instructions for the air conditioner service station or purging device for refrigerant circuits.
The filter in the purging device for refrigerant circuits should be changed after about 2 purging cycles (purged vehicles), depending on the level of contamination from the purged refrigerant circuits. If a heavily contaminated refrigerant circuit is purged (the refrigerant oil from the refrigerant circuit is black and viscous or there are large amounts of shavings in the refrigerant circuit) renew filter after purging refrigerant circuit. After such heavy contamination of the refrigerant circuit, we suggest purging the system again after changing the filter.
Depending on the type of contamination, deposits (old refrigerant oil and abrasive wear particles from the air conditioner compressor) will gather in the sight glass(es) of the purging device for refrigerant circuits. Clean sight glass(es) after purging and purge refrigerant circuits again.
Fluid refrigerant cannot flow at the necessary speed through the expansion valve, the restrictor and the dryer cartridge of certain receivers. These components must therefore be removed and an adapter installed in their place → Heating, air conditioning.
Adapters to connect air conditioner service station and to bridge certain components of refrigerant circuit → Chapter.
–  Switch on the air conditioner service station and purge the refrigerant circuit (duration approx. 1 to 1.5 hours for one purging cycle with three purgings using approx  4 Kg refrigerant R134a).
  Note
The purging process of the refrigerant circuit should be carried out in accordance with the operating instructions of the air conditioner service station
Depending on the type of air conditioner service station, the waste oil container has a capacity of only approx. 125 cm3. If a system with a greater amount of refrigerant oil has to be purged, it may be necessary to empty the waste oil container after the first purge of the purging cycle.
Watch the refrigerant that flows out of the refrigerant circuit. When the refrigerant flows through the sight glass of the purging device into the air conditioner service station clear and completely free of colour, the refrigerant circuit is cleaned.
When purging, the whole amount of refrigerant oil from the refrigerant circuit is cleaned (except for a small amount in the evaporator, though this is not important).
Where contamination is particularly high, it may be necessary to carry out the purging cycle twice (two purging cycles with three purges each). Purging device filter must be renewed before starting second purging cycle.
Sequence of purging process (sequence is carried out automatically in accordance with the air conditioner service station programme)
After switching on, the purging cycle (refrigerant circuit with connection hoses and purging device for refrigerant circuits) is first evacuated and the refrigerant circuit thereby checked for leaks. Depending on the type of air conditioner service station, it may be necessary to continue the sequence manually.
In the evacuated purging circuit, a predetermined amount of refrigerant is filled (e.g. 4 kg) via the high-pressure side of the air conditioner service station (against the normal direction of flow for air conditioner operation and thereby on the low-pressure side of the vehicle refrigerant circuit). Depending on the type of air conditioner service station, refrigerant is filled until the purging circuit is completely filled with liquid refrigerant. This can be identified, for example, by the fact that after a certain period of time no more refrigerant flows through.
Once the predetermined amount of refrigerant has been filled in the system, the heater, for example, of the purging device for refrigerant circuits is switched on depending on the type of air conditioner service station and purging device for refrigerant circuits (only if the refrigerant is extracted in gaseous form out of the purging device for refrigerant circuits).
When the refrigerant has been extracted, the heater of the purging device (if fitted) for refrigerant circuits is switched off, the refrigerant circuit may have to be evacuated briefly again depending on the design, and following evacuation so that the air conditioner service station can separate out the refrigerant oil.
The sequence for filling with refrigerant, extracting (and evacuating) is carried out twice (that means a total of three times).
After extracting for the third time, the purging circuit is evacuated depending on the type of air conditioner service station.
–  Once the purging cycle is complete, check the sight glass (or sight glasses) for refrigerant circuits. If this is dirty, clean it in accordance with the operating instructions of the purging device for refrigerant circuits or the air conditioner service station. Carry out a purging cycle once more as a precautionary measure. One purging cycle is sufficient (approx. 30 min.).
–  Check the pressure in the refrigerant circuit. There must be no pressure in the refrigerant circuit (evacuate again briefly if necessary).
–  Remove the connections to the air conditioning service station from the refrigerant circuit of the vehicle (there should be no pressure in the refrigerant circuit)
–  Renew these components according to the type of vehicle.
Restrictor and reservoir
Expansion valve and receiver or dryer cartridge in receiver
–  → Heating, air conditioning and → Parts catalogue.
–  Replace air conditioner compressor depending on complaint → Heating, air conditioning and → Parts catalogue or drain the remaining refrigerant oil from the removed air conditioner compressor → Chapter (renewing components of refrigerant circuit) and fill it with the prescribed amount of fresh refrigerant oil → vehicle-specific workshop manual.
  Note
There is a predetermined amount of refrigerant oil in the genuine air conditioner compressor. On vehicles with two evaporators, a certain amount of refrigerant oil may have to be added to the circuit as appropriate → vehicle-specific workshop manual.
If the air conditioner compressor does not have to be renewed, the volume of refrigerant oil in the air conditioner compressor must be replenished in accordance with the fill volume (pour out refrigerant oil and refill the prescribed amount in the air conditioner compressor or the refrigerant circuit) → Chapter (renewing components of refrigerant circuit) and → vehicle-specific workshop manual.
–  Assemble the refrigerant circuit back together again completely → Heating, air conditioning.
–  Evacuate and fill the refrigerant circuit as per specifications → Chapter and → Chapter.
–  Bring the air conditioning system into operation as per specifications → Heating, air conditioning and → Chapter.
 

Purging (cleaning) refrigerant circuit with refrigerant R134a

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Principle circuit diagrams for various purging circuits
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