Refrigerant Circuit, Flushing (Cleaning) With Refrigerant R134a

Refrigerant Circuit, Flushing (Cleaning) With Refrigerant R134a

- Refrigerant circuit must be flushed with refrigerant R134a in order to force out contaminants (e.g. abraded material from a malfunctioning A/C compressor) as well as old refrigerant oil as efficiently and as cleanly as possible and without the need for extensive work.

NOTE: Flushing a refrigerant circuit is shown in Volkswagen ServiceNet; API/PKW or Volkswagen TV API Online; then General Information and 08.06.05 Refrigerant circuit, flushing on Golf Plus.

The refrigerant circuit should be flushed with refrigerant R134a if:
- dirt or other contamination is in the refrigerant circuit.
- vacuum reading is not maintained on evacuating a leak-free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit).
- refrigerant circuit has been left open for longer than normal (e.g. following an accident).
- If pressure and temperature measurements in the refrigerant circuit indicate the likelihood of moisture in the circuit.
- In the event of doubt about the amount of refrigerant oil in the circuit. If the A/C compressor should be reinstalled, the refrigerant should be drained from the compressor via the drain plug (replace O-ring). To facilitate this, the ribbed belt pulley or magnetic clutch plate on the A/C compressor should be rotated by hand. After flushing, the entire quantity of refrigerant oil specified by should be added to the refrigerant circuit (50 grams directly in the A/C compressor). Note additional oil quantity for systems with a 2nd evaporator.
- A/C compressor had to be replaced on account of internal damage (e.g. noise or no output).
- stipulated by the vehicle-specific information following replacement of certain components.

Tools required
- A/C service station with flushing device VAS 6380 or A/C service station with flushing device VAS 6337. The auxiliary function "Flush refrigerant circuit" and the refrigerant circuit flushing device required for it are present on these A/C service stations Special Tools Catalog.
- VW/Audi passenger vehicle set adapter chest VAS 6338/1 and Workshop equipment and special tools catalog.
- Commercial vehicle set adapter chest VAS 6338/50 and Workshop equipment and special tools catalog.

NOTE:
- If neither of the two A/C service stations listed above are available for use in the workshop, Refrigerant Circuit Flushing Device VAS 6336/1 or Refrigerant Circuit Flushing Device VAS 6337/1 (depending on the workshop A/C service station version) (min. 7 kg refrigerant R134a in refrigerant bottle) can also be used to flush the refrigerant circuit. However, the flushing procedure must then be performed manually.
- In vehicles with screw-connections on refrigerant circuit, adapter V.A.G 1785/1 up to adapter V.A.G 1785/8 from VW/Audi passenger vehicle set adapter chest VAS 6338/1 or commercial vehicle set adapter chest VAS 6338/50 may be used. In vehicles with screw-connections on A/C compressor and on accumulator, two of the adapters V.A.G 1785/8 are required.
- A charging hose VAS 6338/31 with 5/8 - 18 UNF connections and large internal diameter can be found in the adapter chests in order to be able to bridge components (it is commercially available).

Preparation
- Discharge refrigerant circuit.
- Remove A/C compressor Heating Air Conditioning.
On a vehicle with restrictor and reservoir.

- Remove restrictor (specific to vehicle) and reconnect refrigerant pipes to each other Heating Air Conditioning.
- Remove reservoir (specific to vehicle) Heating Air Conditioning and connect refrigerant pipes to each other (to do this, use adapter and charge hose VAS 6338/31) from VW/Audi passenger vehicle set adapter chest VAS 6338/1.

NOTE: The reservoir could be flushed, however it requires too much fluid refrigerant due to its large internal volume. When this refrigerant is extracted, the reservoir ices up severely and this prolongs the extraction process significantly.

On a vehicle with expansion valve and fluid reservoir.
- Remove fluid reservoir Heating Air Conditioning (specific to vehicle, not required for all vehicles) and connect refrigerant pipes to each other (for this, use adapters and charging hose VAS 6338/31).
- Remove expansion valve Heating Air Conditioning (specific to vehicle) and install the adapter for it.

NOTE: If no suitable adapter for the expansion valve is available in Adapter Set for Refrigerant Circuits VAS 6338/1 or Commercial Vehicle Adapter Set Chest VAS 6338/50, the remove expansion valve can also be drilled open (the expansion valve must be replaced with a new one).

CAUTION:
- Make sure that sealing surfaces on expansion valve are not damaged when drilling open.
- Otherwise refrigerant leaks out.

NOTE:
- Several components are to be removed from expansion valve before drilling open.
- Expansion valves are available in different versions. For version -A-, components -B-, -C- and -D- must be removed. Then separate regulating element -E- from component -D-. Then drill open expansion valve in area -F- using a suitable drill (6 mm diameter).
- For version -G-, parts -H-, -I- and -K- must be removed and then drill open area -L- using suitable drill (6 mm diameter).
- Clean the drilled open expansion valve of residue from the work (shavings).
- Install parts -B-, -C- and -D- for version -A- or -H- for version -G-.

NOTE: In vehicles with two evaporators, the circuit to the second evaporator must be disconnected from circuit of the first evaporator and must be flushed via a separate work procedure.

Flushing
- Check refrigerant quantity in the refrigerant cylinder, there must be at least 7 kg of refrigerant R134a.

NOTE:
- If necessary, switch on the heater installed on the refrigerant cylinder for 30 minutes before the first flushing procedure. This increases pressure in the refrigerant cylinder and accelerates charging of the flushing circuit.
- Drain the old oil container of the A/C service station.
- Connect supply hose (high pressure side) of A/C service station via an adapter to the low pressure line to the A/C compressor (line with larger diameter).
- Connect return hose (low pressure- or intake side) of A/C service station to output of refrigerant circuit flushing device.
- Connect input of refrigerant circuit flushing device via an adapter to the high pressure line to the A/C compressor (line with smaller diameter).

NOTE:
- Components are always flushed in the opposite direction of refrigerant flow when A/C system is in operation.
- While flushing, contaminants from the refrigerant circuit enter the refrigerant circuit flushing device and the A/C service station and are absorbed by the filters and dryers installed there. Depending on the contaminant, these components are to be replaced in shorter intervals in line with operating instructions for A/C service station or refrigerant circuit flushing device.
- The filter in the refrigerant circuit flushing device depends on the type and degree of contamination in the flushed refrigerant circuit, it should be changed after 5 to 10 flushing cycles at the latest. If a heavily contaminated refrigerant circuit is flushed (the refrigerant oil from the circuit is black and viscous or there are many shavings in the refrigerant circuit), the filter should be replaced after flushing. With a refrigerant circuit heavily contaminated in this way, it is wise to flush the circuit again after changing the filter.
- Depending on the type of contamination, dirt (old refrigerant oil and abraded material from A/C compressor) is deposited on the viewing glass(es). Clean viewing glass(es) after flushing and flush the refrigerant circuit once more with one flushing procedure as a check.
- Fluid refrigerant cannot be conducted with the necessary speed through the expansion valve, restrictor and desiccant bag of certain fluid reservoirs, therefore these components must be removed and replaced by an adapter.
- Adapters for connecting A/C service station and for bridging certain components of refrigerant circuit.

- Switch on A/C service station and flush refrigerant circuit (duration approx. 1 to 1.5 hours for one flushing cycle with three flushing operations).

NOTE:
- Perform flushing of refrigerant circuit according to operating instructions of the A/C service station.
- Depending on A/C service station version, the old oil container holds only approx. 125 cu.cm of refrigerant oil. In the event a system with a larger volume of refrigerant oil must be flushed, it may be necessary to empty the old oil container after the first flushing procedure of a flushing cycle.
- Observe the refrigerant which flows back from the refrigerant circuit. Only when the refrigerant streams clear and completely colorless through the viewing glass(es) of refrigerant circuit flushing device in the A/C service station has the refrigerant circuit been cleaned.
- When flushing, the complete amount of refrigerant oil is washed out of the refrigerant circuit (except for minor remains which can be disregarded).
- If contamination is especially severe, it may be necessary to perform the flushing cycle twice (two flushing cycles with three flushing operations each). Before the second flushing cycle, the filter on the flushing device must be replaced.

Sequence of flushing procedure (sequence occurs automatically according to the A/C service station program)
- After switching on, the flushing circuit (refrigerant circuit with connecting hoses and refrigerant circuit flushing device) is first evacuated and the refrigerant circuit is simultaneously checked for leaks. Depending on A/C service station version, it is possible that manually switching to advance the program is required.
- A prescribed amount of refrigerant (e.g. 4 kg) is filled into the evacuated flushing circuit via the high pressure side of the A/C service station (opposite the normal direction of flow during normal A/C system operation and thus on the low pressure side of vehicle refrigerant circuit). Depending on A/C service station version, refrigerant is filled in until the flushing circuit has been completely filled with refrigerant. This can be detected by e.g. refrigerant no longer flowing in after a certain period of time.
- After the prescribed quantity of refrigerant has been filled, e.g. the heater for the refrigerant circuit flushing device is switched on (only in the event the refrigerant is extracted in gaseous form from the refrigerant circuit flushing device), depending on version of A/C service station and refrigerant circuit flushing device.
- After the refrigerant has been extracted, heater of refrigerant circuit flushing device (if present) is switched off, refrigerant circuit is possibly evacuated briefly anew depending on the version, and the refrigerant oil extracted from the refrigerant circuit is separated by the A/C service station after evacuating.
- The sequence of filling refrigerant, extracting (and evacuating) is repeated twice (performed a total of three times).
- After the third extraction, the flushing circuit is evacuated depending on the version of the A/C service station.
- After flushing cycle has ended, check viewing glass(es) of refrigerant circuit flushing device, if they are dirty, clean them in line with the operating instructions of refrigerant circuit flushing device or A/C service station. Perform one addition flushing cycle as a check. One flushing procedure is sufficient (approx. 30 min.)
- Check pressure in refrigerant circuit, there must be no positive pressure in the refrigerant circuit (evacuate refrigerant circuit briefly once more if necessary).
- Disconnect A/C service station connections from vehicle refrigerant circuit. There must be no positive pressure in the refrigerant circuit.
- Replace these vehicle-specific components.

- Restrictor and reservoir
- Expansion valve and fluid reservoir or dryer cartridge in fluid reservoir
- Depending on the complaint, replace A/C compressor Heating Air Conditioning and Parts Catalog or drain the remaining refrigerant oil from the removed A/C compressor (replace refrigerant circuit components) and re-fill the prescribed quantity of fresh refrigerant oil vehicle-specific Repair information.

NOTE:
- A certain prescribed quantity of refrigerant oil is in the A/C compressor original part. On vehicles with two evaporators, a certain quantity of refrigerant oil must also be added to the circuit if necessary.
- If the A/C compressor is not be replaced, the quantity of refrigerant oil in the A/C compressor must be topped off to the prescribed capacity (tilt the refrigerant oil out and refill the prescribed quantity into the A/C compressor or refrigerant circuit) (replacing refrigerant circuit components) and Heating Air Conditioning.

- Completely reassemble the refrigerant circuit Heating Air Conditioning.
- Evacuate and recharge refrigerant circuit according to specification.
- Start up A/C system according to specification Heating Air Conditioning and A/C system, operating after charging.

Block diagrams for various flushing circuits

NOTE:
- The arrows in the following illustrations show the direction of refrigerant flow while flushing. During flushing, refrigerant flows in the opposite direction than during A/C system operation, therefore the high pressure side of A/C service station is connected to A/C compressor at low pressure side of refrigerant circuit.
- These block diagrams show a refrigerant circuit with restrictor and reservoir and a refrigerant circuit with expansion valve, fluid reservoir and a second evaporator (optional equipment on certain vehicles).
- Depending on the design of A/C service station, check-valves may be installed between refrigerant circuit and A/C service station. They guarantee the correct direction of refrigerant flow during flushing.

Refrigerant circuit with restrictor and reservoir

NOTE: On vehicles with restrictor and reservoir, the restrictor and reservoir are removed. Restrictor refrigerant pipes are reassembled. Refrigerant pipes to the removed reservoir are connected with each other via two adapters and charge hose VAS 6338/31 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1).







1. A/C service station
- With electronics and a flushing program, e.g. A/C service station with flushing device VAS 6380 or A/C service station with flushing device VAS 6337.
- If an A/C service station without a flushing program is used, the procedure must be performed manually (evacuate, flush 3 times with at least 4 kg refrigerant each and extract refrigerant again, evacuate).

2. Refrigerant hose of A/C service station
- From high pressure side of A/C service station (mostly colored red) to low pressure side connection of A/C compressor on refrigerant circuit (larger diameter).

3. Adapter to connection for low pressure side on refrigerant circuit
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1

4. Low pressure side connection on refrigerant circuit
- Different versions depending on vehicle.
- On refrigerant line from A/C compressor to reservoir.

5. Connection to reservoir
- Different versions depending on vehicle.
- On refrigerant line from A/C compressor to reservoir.

6. Adapter for bridging the removed reservoir
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1

7. Refrigerant charge hose
- Charge hose VAS 6338/31 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1) for example.

8. Adapter for bridging the removed reservoir
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1

9. Connection to reservoir
- Different versions depending on vehicle.

10. Evaporator
11. Component location of restrictor
- Restrictor is removed.
- Remove restrictor Heating Air Conditioning.

12. Bolts in refrigerant line
- Bolt together again after removing restrictor Heating Air Conditioning.

13. Condenser
14. High pressure side connection on refrigerant circuit
- Different versions depending on vehicle

15. Adapter to connection for high pressure side on refrigerant circuit
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1.

16. Charge hose for refrigerant circuit flushing device
- From connection to high pressure side of A/C compressor on refrigerant circuit (smaller diameter) to input of Refrigerant Circuit Flushing Device VAS 6336/1 or Refrigerant Circuit Flushing Device VAS 6337/1.

17. Refrigerant circuit flushing device
- Different versions and different construction, e.g. refrigerant circuit flushing device VAS 6336/1 or refrigerant circuit flushing device VAS 6337/1.
- With filter, viewing glass, security valve, heater, refrigerant container, etc. (depending on version).
- Depending on the construction of the A/C service station and of refrigerant circuit flushing device, a check-valve may be installed at output of refrigerant circuit flushing device (to guarantee correct direction of refrigerant flow during flushing).

18. Refrigerant hose of A/C service station
- From low pressure side of A/C service station (mostly colored blue) to output of refrigerant circuit flushing device.

Refrigerant circuit with expansion valve, fluid reservoir and second evaporator

NOTE:
- This block diagram shows a refrigerant circuit with expansion valve, fluid reservoir and second evaporator (optional equipment on certain vehicles).
- On vehicles with expansion valve and fluid reservoir, the expansion valve is removed and replaced by an adapter. Depending on vehicle, fluid reservoir is flushed or dryer cartridge is removed. Depending on fluid reservoir version, it is to be removed and line connections to fluid reservoir are to be connected to each other with two adapters and a charging hose.
- On a vehicle with only one evaporator, components from item "16" are not present or are not needed.







1. A/C service station
- With electronics and a flushing program, e.g. A/C service station with flushing device VAS 6380 or A/C service station with flushing device VAS 6337.
- If an A/C service station without program is used for flushing, the procedure should be performed manually.
- Extract the refrigerant, if necessary.
- Set up Refrigerant Circuit Flushing Device VAS 6336/1 or Refrigerant Circuit Flushing Device VAS 6337/1 between service station and refrigerant circuit return line.
- Evacuate refrigerant circuit for 20 minutes and then charge with 4 kg refrigerant R134a. Then extract again and repeat the procedure 2 more times. If the refrigerant in the sight glass(es) is not clear after the 3rd procedure, an additional procedure is necessary.

2. Refrigerant hose of A/C service station
- From high pressure side of A/C service station (mostly colored red) to low pressure side connection of A/C compressor on refrigerant circuit (larger diameter).

3. Adapter to connection for low pressure side on refrigerant circuit
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1.

4. Low pressure side connection on refrigerant circuit
- Different versions depending on vehicle.

5. Adapter for the removed expansion valve
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1.

6. Evaporator
7. Connection to fluid reservoir
- Different versions depending on vehicle.
- Not present on vehicles with a dryer cartridge in fluid reservoir on condenser or a fluid reservoir installed in the condenser Heating Air Conditioning.

8. Adapter for bridging the removed fluid reservoir
- Not required for all vehicles.
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1.

9. Refrigerant charge hose
- Charge hose VAS 6338/31 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1) for example.

10. Condenser
- If a fluid reservoir with dryer cartridge is installed on the condenser, dryer cartridge must be removed (seal again the fluid reservoir on or in the condenser after removing) Heating Air Conditioning.
- If fluid reservoir is built directly on the condenser, fluid reservoir is to be removed and replaced only after flushing Heating Air Conditioning.

11. High pressure side connection on refrigerant circuit
- Different versions depending on vehicle.

12. Adapter to connection for high pressure side on refrigerant circuit
- Different versions depending on vehicle.
- From VW/Audi passenger vehicle set adapter chest VAS 6338/1.

13. Charge hose for refrigerant circuit flushing device
- From connection to the high pressure side of the A/C compressor on the refrigerant circuit (smaller diameter) to input of refrigerant circuit flushing device.

14. Refrigerant circuit flushing device
- Different versions and different construction, e.g. refrigerant circuit flushing device VAS 6336/1 or refrigerant circuit flushing device VAS 6337/1.
- With filter, viewing glass, security valve, heater, refrigerant container, etc. (depending on version).
- Depending on the construction of the A/C service station and of refrigerant circuit flushing device, a check-valve may be installed at output of refrigerant circuit flushing device (to guarantee correct direction of refrigerant flow during flushing).

15. Refrigerant hose of A/C service station
- From low pressure side of A/C service station (mostly colored blue) to output of refrigerant circuit flushing device.

16. Adapter for sealing outlet to the second evaporator
- Only required for certain vehicles with optional equipment "2nd evaporator".
- From commercial vehicle set adapter chest VAS 6338/50.

17. Adapter for sealing outlet to the second evaporator
- Only required for certain vehicles with optional equipment "2nd evaporator"
- From commercial vehicle set adapter chest VAS 6338/50.

18. Low pressure side connection on refrigerant circuit to second evaporator
- Different versions depending on vehicle.
- Only present on certain vehicles with optional equipment "2nd evaporator".

19. High pressure side connection on refrigerant circuit to second evaporator
- Different versions depending on vehicle.
- Only present on certain vehicles with optional equipment "2nd evaporator"

20. Adapter for the removed expansion valve on second evaporator
- Different versions depending on vehicle.
- Only required for certain vehicles with optional equipment "2nd evaporator".
- From commercial vehicle set adapter chest VAS 6338/50.

21. Second evaporator
- Only present on certain vehicles with optional equipment "2nd evaporator"

Adapter for assembling the flushing circuit
- Various adapters which are required to connect the A/C service station to the refrigerant circuit for flushing and to bridge the removed fluid reservoir or reservoir and expansion valve (specific to vehicle) are in the following table.
- Using a charge hose with 5/8 -18 UNF connections (short version, e.g. charge hose VAS 6338/31), connect the two adapters (contained in VW/Audi passenger vehicle set adapter chest VAS 6338/1) which have been installed for the removed reservoir or fluid reservoir.
- If a flushed refrigerant circuit is not to be reassembled immediately after the flushing, leave the adapters on the connections and seal the connections on the adapters with sealing caps VAS 6338/30 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1).
- Depending on the version of the A/C compressor and on the time period of production, various connecting and sealing technologies can be found on the refrigerant circuit.







Block or screw connections

Screw connection -A-

Block connection - B -







Block connections with different types of seal

Block connection with radially sealed connection -A- (with plastic or metal guide - B -)

Block connection with axially sealed connection - C -

Jetta 2006; New Beetle 1999; New Beetle Cabrio 2003; Eos 2006; Bora 1999