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Block diagrams for various flushing circuits > < Blowing out refrigerant circuit

A3 Mk2

Flushing (cleaning) refrigerant circuit with refrigerant R134a
Flushing (cleaning) refrigerant circuit with refrigerant R134a
Vehicles with high-voltage system (hybrid vehicles)
For all work on vehicles with a high-voltage system, note the additional warning instructions for working on such vehicles → Chapter „Warning instructions when working on vehicles with high-voltage system“ and → Electrical system; Rep. gr.93.
  WARNING
Safety hazard: the engine can start unexpectedly.
Before carrying out general work on a vehicle with high-voltage electrical system, switch off the ignition and remove the ignition key from the vehicle.
  WARNING
Working on vehicles with high-voltage wiring:
l  Do not support yourself or tools on high-voltage wiring or associated components --> this can damage the insulation.
l  High-voltage wiring must not be excessively bent or kinked --> this can damage the insulation.
l  The round high-voltage connectors are colour-coded with an external coloured ring and are provided with mechanical coding or guide lugs. It is important to observe this coding when joining up the round high-voltage connectors, otherwise the connectors can be damaged.
  DANGER!
Risk of fatal injury if high-voltage components are damaged.
Observe the following when working in the vicinity of high-voltage components or wiring:
t  It is not permitted to use cutting or forming tools, other sharp-edged tools or heat sources such as welding, brazing, soldering, hot air or thermal bonding equipment.
t  Before starting work, visually inspect the high-voltage components in the areas involved.
t  Before working in the engine compartment, visually inspect the power electronics -JX1-, electric drive motor -V141-, air conditioner compressor -V470- and high-voltage wiring.
t  Before working on the vehicle underbody, visually inspect the high-voltage wiring and covers.
t  Before working on the rear section of the vehicle, visually inspect the high-voltage wiring and the electro-box with the maintenance connector for high-voltage system - TW -.
t  Visually inspect all potential equalisation lines.
Check the following when making the visual inspection:
t  There must be no external damage on any component.
t  The insulation of the high-voltage wiring and potential equalisation lines must not be damaged.
t  There must be no unusual deformation of the high-voltage wiring.
t  All high-voltage components must be identified by a red warning sticker.
If work is necessary in the vicinity of high-voltage system components, perform a visual inspection of the high-voltage components and wiring to check for damage → Chapter and note → Electrical system; Rep. gr.93.
If work is necessary on high-voltage system components, de-energise the high-voltage system → Electrical system; Rep. gr.93 and note → Electrical system; Rep. gr.93.
De-energising high-voltage system
  DANGER!
Voltage can cause fatal injury.
Danger of severe or fatal injuries from electric shock.
t  For reasons of safety, persons with life-preserving or other electronic medical devices in or on their body must not perform any work on the high-voltage system. Such medical devices include internal analgesic pumps, implanted defibrillators, pacemakers, insulin pumps and hearing aids.
t  The high-voltage system may only be de-energised by a suitably qualified person (Audi high-voltage technician).
t  It must be definitely confirmed that the high-voltage system is de-energised. The system may only be de-energised using the vehicle diagnostic tester via „Guided Fault Finding“.
t  The qualified person (Audi high-voltage technician) confirms that the system is de-energised and uses the locking cap -T40262- to ensure that the system cannot be re-energised. The ignition key and the maintenance connector for high-voltage system - TW - should then be stored in a safe place by the qualified person.
t  The qualified person (Audi high-voltage technician) marks the vehicle by attaching the appropriate warning signs.
  Note
t  De-energising high-voltage system:
t  Connect vehicle diagnostic tester
t  Select Guided Fault Finding mode
t  Using the Go to key, select the following menu items in succession
t  Function/component selection
t  Body
t  Electrical system
t  Self-diagnosis compatible systems
t  8C - Hybrid battery management -J840
t  8C - Hybrid battery management, functions
t  51 - De-energise high-voltage system (Rep. gr. 93)
Re-energising high-voltage system
  DANGER!
Voltage can cause fatal injury.
Danger of severe or fatal injuries from electric shock.
t  For reasons of safety, persons with life-preserving or other electronic medical devices in or on their body must not perform any work on the high-voltage system. Such medical devices include internal analgesic pumps, implanted defibrillators, pacemakers, insulin pumps and hearing aids.
t  The high-voltage system may only be re-energised by a suitably qualified person (Audi high-voltage technician).
t  The system may only be re-energised using the vehicle diagnostic tester via „Guided Fault Finding“.
t  The vehicle is then made ready for operation again by the qualified person (Audi high-voltage technician).
t  The qualified person (Audi high-voltage technician) marks the vehicle by attaching the appropriate warning signs.
  Note
t  Re-energise high-voltage system:
t  Connect vehicle diagnostic tester
t  Select Guided Fault Finding mode
t  Using the Go to key, select the following menu items in succession
t  Function/component selection
t  Body
t  Electrical system
t  Self-diagnosis compatible systems
t  8C - Hybrid battery management -J840
t  8C - Hybrid battery management, functions
t  51 - Re-energise high-voltage system (Rep. gr. 93)
  DANGER!
When working on a vehicle with the ignition switched on or while the drive system is active, the engine can start unexpectedly and exhaust fumes can cause a health hazard in closed rooms. Moving parts can trap or draw in parts of the body and/or clothing (safety hazard).
Before switching on the ignition, perform the following steps:
t  Move selector lever to position P
t  Activate parking brake
t  Switch off ignition
t  Open bonnet
t  Connect battery charger (e.g. -VAS 5095A-) to jump-start connections of 12 V electrical system
t  Switch on ignition
–  To minimise the number of automatic engine starts when the vehicle's drive system is active during test and measurement work, charge the vehicle batteries e.g. with the battery charger 60A -VAS 5904- in battery standby mode → Electrical system; Rep. gr.27 and → Electrical system; Rep. gr.93.
–  For test and measurement work that requires the vehicle's drive system to be active or the ignition to be switched on, move the selector lever to position „P“, activate the parking brake and arrange the tools needed so that they cannot come into contact with moving components of the engine and so that they cannot even come near to components that turn when the engine is running.
  Note
t  Move the selector lever to position „P“ and activate the parking brake before performing test and measurement work for which the ignition must be switched on but where the vehicle's drive system does not need to be active.
t  The status of the drive system is shown by the control unit in dash panel insert -J285- via the „power meter“ → Owner's Manual.
t  Activating and deactivating drive system → Owner's Manual (note display of control unit in dash panel insert -J285-).
All vehicles
  Caution
t  If there is a possibility that chemical substances (sealing additives) for sealing leaks have been added to the refrigerant circuit to be flushed, do not connect the air conditioner service station to this refrigerant circuit and do not flush this refrigerant circuit.
t  Chemical substances (sealing additives) for sealing leaks form deposits in the refrigerant circuit which will impair operation of the air conditioning system and lead to failure of the system (and of the air conditioner service station).
t  Customers should be informed that the air conditioner in their vehicle contains substances not approved by Audi and that the system can therefore not be flushed and serviced by your workshop.
  Note
t  Audi does not permit the use of chemical substances (sealing additives) to seal leaks in the refrigerant circuit.
t  Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit generally react with the ambient air or the humidity contained in it. They cause malfunctioning of valves and other components with which they come into contact on account of deposits in the refrigerant circuit (and in the air conditioner service station being used). These deposits cannot be completely removed from the components affected (even by flushing). The refrigerant circuit can therefore only be repaired by renewing all the components which have come into contact with this substance.
t  Chemical substances (sealing additives) for sealing leaks in the refrigerant circuit are normally not outwardly apparent and the identification stickers which should be affixed for this purpose are usually non-existent. Vehicles with an unknown history should therefore be treated with due caution.
l  The best way of removing moisture, impurities (e.g. abrasion from a defective air conditioner compressor) and old refrigerant oil without any unnecessary loss of refrigerant and without extensive assembly work, whilst at the same time ensuring environmental compatibility, is to flush the refrigerant circuit with refrigerant R134a.
The refrigerant circuit is to be flushed:
–  In there is any dirt or similar in the circuit.
–  If vacuum reading is not maintained on evacuating a leak-free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit)
–  If the refrigerant circuit has been left open for longer than the normal assembly time (e.g. following an accident).
–  If pressure and temperature measurements in the refrigerant circuit indicate the likelihood of moisture.
–  If there are doubts about the amount of refrigerant oil in the refrigerant circuit.
–  If the air conditioner compressor has to be renewed on account of internal damage (e.g. noise or no output).
–  If stipulated by the vehicle-specific workshop manual following replacement of certain components.
Tools required
t  Air conditioner service station with flushing attachment (these air conditioner service stations feature the additional function „Flushing refrigerant circuit“ and the necessary flushing attachment for refrigerant circuits) → Workshop equipment and special tools catalogue
t  Adapter set for refrigerant circuits -VAS 6338/1- → Chapter and → Workshop equipment and special tools catalogue
t 
  Note
t  If no air conditioner service station with flushing attachment is available → Workshop equipment and special tools catalogue and depending on the version of the air conditioner service station being used, the refrigerant circuit can also be flushed with this employing the refrigerant circuit flushing attachment → Workshop equipment and special tools catalogue, however flushing must then be performed manually. → Anchor
t  Use can be made for vehicles with screw connections at the refrigerant circuit of the adapter -V.A.G 1785/7- and adapter -V.A.G 1785/8- from the VW/Audi passenger vehicle adapter set -VAS 6338/1-. Two adapters -V.A.G 1785/8- are required for a vehicle with screw connections at the air conditioner compressor and reservoir.
t  The adapter set for refrigerant circuits -VAS 6338/1- also contains a short filler hose -VAS 6338/31- with 5/8 -18 UNF connections and a large inside diameter (commercially available).
Preparation
–  Discharge the refrigerant circuit → Chapter.
–  Remove the air conditioner compressor → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
Vehicle with restrictor and reservoir
–  Remove restrictor (vehicle-specific) and re-connect pipes → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific Workshop Manual).
–  Remove the reservoir (vehicle-specific) and re-connect the lines (for this purpose, make use of an adapter and the charging hose -VAS 6338/31- from the VW/Audi passenger vehicle adapter set -VAS 6338/1-) → Chapter, → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
  Note
It would be possible to flush the reservoir, however on account of its large internal volume it holds too much liquid refrigerant. On extracting this refrigerant, the reservoir would ice up severely, the refrigerant would only evaporate very slowly and the extraction process would be excessively long.
Vehicle with expansion valve and receiver
–  Remove the receiver (vehicle-specific, not necessary with all vehicles) and re-connect the lines (for this purpose, make use of an adapter and the charging hose -VAS 6338/31- from the VW/Audi passenger vehicle adapter set -VAS 6338/1-) → Chapter, → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
  Note
t  Depending on design, the receiver can be flushed (remove the fitted dryer cartridge if applicable) → Chapter, → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
t  If the receiver is attached to the condenser (e.g. on Audi A3 as of Model Year 2004), it is not removed for flushing (its design makes it suitable for flushing and it is only renewed after flushing) → Chapter and → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
t  In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately or which are not available separately, the condenser is to be renewed after flushing. On these vehicles, the condenser is then to be renewed together with the receiver → Heating, air conditioning; Rep. gr.87 and → Electronic parts catalogue.
t  Depending on the version, receivers on which the dryer cartridge can be renewed separately may be provided with an additional filter element which may have to be renewed together with the dryer cartridge.
–  On vehicles with a dryer cartridge in the receiver at the condenser (vehicle-specific), remove the dryer cartridge and re-seal the opening at the receiver → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
–  Remove the expansion valve (vehicle-specific) and replace it with an adapter from the VW/Audi passenger vehicle adapter set -VAS 6338/1- → Chapter, → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
  Note
If there is no suitable adapter for the expansion valve in the VW/Audi passenger vehicle adapter set -VAS 6338/1-, the expansion valve removed can also be drilled open (the old expansion valve generally has to be renewed and is therefore no longer needed).
  Caution
t  Take care not to damage the sealing surfaces at the expansion valve when drilling it open.
t  Otherwise, refrigerant will escape at damaged sealing surfaces.
  Note
   
t  Before drilling open, remove the control element and then drill open the expansion valve using a suitable drill bit for example (bit diameter e.g. 6.0 mm).
t  Certain components have to be removed from the expansion valve before drilling it open.
t  There are different expansion valve versions with differing design. With version -A-, the parts -B-, -C- and -D- have to be removed for example. Then separate part -E- (control element) from part -D-. After doing so, use a suitable bit to drill open the expansion valve in area -F-.
t  With version -G-, the parts -H-, -I- and -K- must be removed for example and the area -L- then drilled open using a suitable bit.
–  Remove swarf remnants from the expansion valve after drilling open.
–  Re-install the parts -B-, -C- and -D- with version -A- or part -H- with version -G-.
  Note
On vehicles with two evaporators, the circuit to the second evaporator is to be separated from the circuit of the first evaporator and flushed in a separate operation → Chapter, → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
Flushing
–  Check the amount of refrigerant in the air conditioner service station, it must contain at least 7 kg of refrigerant R134a.
  Note
If applicable, switch on the heater attached to the air conditioner service station for the refrigerant cylinder installed in the air conditioner service station prior to the first flushing operation (to increase the pressure in the refrigerant cylinder) and switch it off again before the first extraction operation during the flushing cycle.
–  Discharge the used oil container of the air conditioner service station.
–  Connect the supply hose (high-pressure end) of the air conditioner service station with an adapter to the low-pressure pipe to the air conditioner compressor (pipe with larger diameter) → Chapter.
–  Connect the return hose (low-pressure or suction end) of the air conditioner service station to the outlet of the refrigerant circuit flushing attachment.
–  Connect the inlet of the refrigerant circuit flushing attachment with an adapter to the high-pressure line to the air conditioner compressor (line with smaller diameter) → Chapter.
  Note
t  The components are always flushed in the direction opposite to that of refrigerant flow during air conditioner operation → Chapter.
t  When flushing, impurities from the refrigerant circuit ingress into the refrigerant circuit flushing attachment and the air conditioner service station, where they are retained in the built-in filters and dryer. Depending on the nature of the impurities, these components are to be renewed more frequently in line with the operating instructions for the air conditioner service station or the refrigerant circuit flushing attachment.
t  Depending on the nature and severity of the contamination of the flushed refrigerant circuits, the filter in the refrigerant circuit flushing kit should be renewed at the latest after 5 to 10 flushing cycles (flushed vehicles). After flushing a severely contaminated refrigerant circuit (the refrigerant oil from the refrigerant circuit is black and viscous or there is a lot of swarf in the refrigerant circuit), the filter is to be renewed. In the case of such severely contaminated refrigerant circuits it is also appropriate to flush the circuit again after renewing the filter.
t  Depending on the nature of the impurities, dirt (used refrigerant oil and abrasion from the air conditioner compressor) accumulates at the inspection port of the refrigerant circuit flushing attachment. If applicable, clean this sight glass after flushing and flush the refrigerant circuit again in one operation as a check (one operation is then sufficient).
t  Liquid refrigerant cannot be routed at the necessary rate through the expansion valve, restrictor and desiccant bag of certain receivers. These components are therefore to be removed and replaced with adapters if applicable → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
t  Adapters for connection of air conditioner service station and for bridging certain refrigerant circuit components → Chapter.
–  Switch on the air conditioner service station and flush the refrigerant circuit (duration approx. 1 to 1.5 hours for one flushing cycle with three flushing operations).
  Note
t  The flushing operation is to be performed in line with the operating instructions for the air conditioner service station.
t  Depending on the version of the air conditioner service station, the used oil container may only hold approx. 125 cm 3 of refrigerant oil. If a system with a larger refrigerant oil quantity is to be flushed, it may be necessary to empty the used oil container after the first flushing operation in a flushing cycle.
t  Observe the refrigerant flowing back out of the refrigerant circuit into the air conditioner service station. Refrigerant circuit cleaning has not been completed until the refrigerant flowing through the inspection port of the refrigerant circuit flushing attachment into the air conditioner service station is clear and completely colourless.
t  During flushing, the entire refrigerant oil is rinsed out of the refrigerant circuit (with the exception of slight residue in the evaporator, for example; this can however be ignored).
t  In the case of extremely severe contamination, it may be necessary to perform flushing twice (two flushing cycles with three flushing operations each).
Sequence of flushing operation (sequence takes place automatically in line with air conditioner service station program)
t  After switch-on, the flushing circuit (refrigerant circuit with connecting hoses and refrigerant circuit flushing attachment) is initially evacuated and the refrigerant circuit checked for leaks (depending on the version of the air conditioner service station, manual switching to next step may be necessary).
t  A specified quantity of refrigerant (e.g. 5 kg) is added to the evacuated refrigerant circuit via the high-pressure end of the air conditioner service station (in the direction opposite to the normal flow direction during air conditioner operation and thus on the low-pressure end of the vehicle refrigerant circuit) or refrigerant is added until the refrigerant circuit and the inspection ports of the refrigerant circuit flushing attachment have been completely filled with liquid refrigerant (depending on the version of the air conditioner service station, the system detects that there has been no further inflow of refrigerant over a certain period for example).
t  Once the specified quantity of refrigerant has been added, the heater of the refrigerant circuit flushing attachment may be switched on for example depending on the version of the air conditioner service station and the refrigerant circuit flushing attachment (only if the refrigerant is extracted in gaseous form from the refrigerant circuit flushing attachment).
t  After the refrigerant has been extracted, the heater of the refrigerant circuit flushing attachment is switched off (if fitted). Depending on the version, the refrigerant circuit may be briefly evacuated again and, following evacuation, the refrigerant oil extracted from the refrigerant circuit is separated by the air conditioner service station.
t  The refrigerant charging, extraction (and evacuation) process is repeated twice (in other words it is implemented a total of three times).
t  Following extraction for the third time, the flushing circuit is evacuated depending on the version of the air conditioner service station.
–  On completion of flushing, check the inspection port(s) of the refrigerant circuit flushing attachment. If these are contaminated, they are to be cleaned if necessary in line with the operating instructions for the refrigerant circuit flushing attachment or air conditioner service station. Flushing is then to be performed again as a check (one operation with a duration of approx. 30 min. is sufficient).
–  Check the pressure in the refrigerant circuit. There must not be any positive pressure in the refrigerant circuit (evacuate briefly again if necessary).
–  Detach the connections to the air conditioner service station from the vehicle refrigerant circuit (there must not be any positive pressure in the refrigerant circuit).
–  Renew the vehicle-specific components (restrictor and reservoir, expansion valve and receiver or dryer cartridge in the receiver) → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual) and → Electronic parts catalogue.
–  Depending on the problem, renew the air conditioner compressor → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual) and → Electronic parts catalogue or drain off the remaining refrigerant oil from the air conditioner compressor removed → Chapter (renew refrigerant circuit components) and add the specified quantity of fresh refrigerant oil again → Chapter (approved refrigerant oils and refrigerant oil capacities).
  Note
t  Replacement compressors contain a certain specified quantity of refrigerant oil. For vehicles with two evaporators, it may be necessary to additionally add a certain quantity of refrigerant oil to the circuit → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual) and → Chapter (approved refrigerant oils and refrigerant oil capacities).
t  If the air conditioner compressor is not to be renewed, the refrigerant oil quantity in the air conditioner compressor must be topped up in line with the specified capacity (pour out refrigerant oil and add the specified quantity to the air conditioner compressor or the refrigerant circuit again) → Chapter (renewing refrigerant circuit components) and → Chapter (approved refrigerant oils and refrigerant oil capacities).
–  Completely re-assemble the refrigerant circuit → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual).
–  Evacuate and charge the refrigerant circuit as specified → Chapter and → Chapter.
–  Start up the air conditioner as specified → Heating, air conditioning; Rep. gr.87 or → Air conditioning; Rep. gr.87 (vehicle-specific workshop manual) and → Chapter.
t  Block diagrams for various flushing circuits → Chapter
t  Adapters for connecting flushing circuits → Chapter
t  Flushing electrically driven air conditioner compressor (removing refrigeration oil) → Chapter
  A87-10130

Block diagrams for various flushing circuits > < Blowing out refrigerant circuit