A/C Unit
A/C Unit
Special tools, testers and auxiliary items required
• Hose Clamps, Up to 40 mm (3093) and Hose Clamps Up to 25 mm diameter (3094)
• Compressed air gun, commercially available
• Hand pump Cooling system tester (V.A.G 1274/) (and corresponding adapter)
Removing
• Before disconnecting the battery, obtain anti-theft radio security code if necessary.
• On vehicles with electrically adjustable seats, move the seats back as far as possible before disconnecting the battery.
• When removing bolts, take note of the length and assignment of bolts for re-installation.
• All cable ties opened or cut during removal of heating & A/C unit must be reinstalled at the same locations during installation.
• Depending on vehicle equipment and on engine, heat insulation has been applied to coolant hoses, these must not be damaged and must be re-applied after installing.
- Discharge the refrigerant circuit.
- Switch off ignition.
- Protect driver and front passenger seats using seat covers.
- Disconnect battery.
- Release pressure in cooling circuit by opening the cap on coolant expansion tank.
- Remove the components that hinder access to the mounting bolts for refrigerant lines - A - on expansion valve and to coolant hoses to heater core in engine compartment.
• Depending on engine and version of vehicle, it may be necessary to loosen or to remove the following components (top engine cover, pressurized air pipe to throttle valve part and depending on engine the intake manifold, etc.).
• Depending on the engine (for example, on certain 2.0L diesel engine, depending on the exhaust system version), it may be necessary to remove the plenum chamber cover and the plenum chamber front wall - A - in order to remove the head shield, and the refrigerant lines from the expansion valve and the coolant hoses to the heater core.
• The heat shield - B - is available in different versions. For version 1, sheet metal nuts - A - must be removed and heat shield - B - disengaged from vehicle.
• On version 2, clamping washers - A - and clamp - C - must be removed and heat shield - B - disengaged from vehicle. After disconnecting coolant hoses, remove heat shield - B - completely.
• For the sake of clarity, the illustrations show the heat shield - B - with the engine removed.
- If present, disengage heat shield - B - from front wall of plenum chamber front wall and from the bulkhead and set it aside (or remove it completely).
- Slide a thermal protective cover - D - and - E - as far back as possible until it is possible to installed the (3093) - F - onto the coolant hoses - A - and - B -.
- Mark arrangement of coolant hoses - A - and - B -.
• The heater core is designed for a specific coolant flow direction, therefore coolant hoses must be connected on the proper sides (coolant hose - A - supply from cylinder head, coolant hose - B - return to coolant pump).
• The coolant hose arrangement is the same in both vehicles without and with A/C, this illustration shows a vehicle with A/C.
• Bleed the coolant circuit.
- If necessary, clamp off vent hose (from upper connection - A - to coolant expansion tank).
- Cover the area beneath connections for coolant hoses - A - and - B -, for example, with a paper towel.
- Clamp off coolant hoses to heater core of heating & A/C unit (using, for example, (3093) ) and remove them.
- Connect one section of hose - A - on to upper connection.
- Hold a container - B - under the lower connection - C -.
- Using a compressed air gun, carefully blow coolant out of heater core (into container - B -).
- Disconnect refrigerant lines from expansion valve. Refer to=> [ Expansion Valve Refrigerant Lines, Disconnecting and Connecting ] Expansion Valve Refrigerant Lines, Disconnecting and Connecting and secure (e.g. with cable tie) so they do not interfere during installation.
• Seal open line connections (against dirt and moisture penetration).
• To seal off all open connections on expansion valve or evaporator, sealing caps from a replacement expansion valve or a replacement evaporator can be used (preventing dirt and moisture from entering the system).
- Remover the glove compartment, the driver side storage compartment, the center console and the instrument panel.
• To prevent the instrument panel shell from damage, instrument panel should be placed on a clean work bench which is covered with clean cardboard.
- Remove the gas pedal module.
- Remove the left and right vents - C -.
- Fold back the carpet on the driver and front passenger sides so that the vents for the rear footwells can be removed - A - and - B -.
- Remove both rear footwell vents - A - and - B -.
- Remove fresh air blower. Refer to => [ Fresh Air Blower Control Module (J126) and Fresh Air Blower (V2) ] Fresh Air Blower Control Module (J126) and Fresh Air Blower (V2).
- Vehicles with manually regulated A/C system: remove A/C system controls, A/C Control Module (J301) (do not remove base plate for controls). Refer to=> [ Heater and A/C System Controls ] Heater and A/C System Controls.
- Remove the instrument panel and the instrument panel crossmember (central tube).
- Remove Data Bus On Board Diagnostic Interface (J533) (secured to bracket - A - in area of steering column).
- Remove bolts - B - and release bracket - A - from A/C unit (bracket remains on wiring harness secured to vehicle).
- Remove both bolts - A - on bracket for wiring harness - B -.
- Disconnect the connector - C -.
- Remove condensation drain from A/C unit. Refer to=> [ Condensate Drain Hose, Checking ] Condensate Drain Hose, Checking.
- Loosen securing ties of wiring harness on A/C unit.
- On vehicles with an electric auxiliary heater (on vehicles with Diesel engine), disconnect wire connections to voltage supply for the auxiliary air heater heating element (Z35). Refer to => [ Auxiliary Air Heater Heating Element (Z35) with Control Module (J604) ] Auxiliary Air Heater Heating Element (Z35) With Control Module (J604).
- Disconnect all electrical connections between vehicle wiring harness and the A/C unit electrical components on connectors.
• The air conditioner wiring harness is removed together with the A/C unit.
- Carefully pull right side of A/C unit slightly toward rear (far enough that bolt - B - on right bracket - A - can be loosened).
• Only pull carefully on A/C unit so that bracket - A - does not break.
• To loosen bolt - B -, reach between A/C unit and floor mat on right wheel housing (to make this possible, fresh air blower has been removed earlier).
- Remove bolts - B - and release bracket - A - from A/C unit (bracket remains on wiring harness secured to vehicle).
- Disengage both flanges for coolant pipes to heater core - A - and for expansion valve (to evaporator) - B - from pass-throughs of grommet - C -.
• When removing A/C unit, make sure the two coolant pipes of the heater core do not get caught and bent or damaged on plenum chamber or noise insulation mat.
• Observe wiring harness, individual electrical wiring connections may get damaged when pulling on harness.
- Remove A/C unit - A - towards passenger side.
Installing
Installation is reverse of removal, noting the following:
- Two technicians are needed to install the heater and A/C unit.
• Before installing, check all gaskets and seals on the A/C unit for damage and replace if necessary.
• Check securing of coolant pipes to heater core.
- Insert molded seal - A - (working from passenger compartment) into bulkhead - B -, make sure that reinforcement - C - (wire bracket) is positioned correctly in molded seal - A -
- Ask a colleague for assistance to install the heating & A/C unit.
- Have the second mechanic (working from engine compartment) guide both flanges for coolant pipes to heater core - A - and for expansion valve (to evaporator) - B - through pass-throughs of grommet - C - when inserting heating & A/C unit.
• When installing A/C unit, make sure the two coolant pipes of the heater core do not get caught and bent or damaged on plenum chamber or noise insulation mat.
• Observe wiring harness, individual electrical wiring connections may get damaged when pulling on harness.
- Connect condensation water drain to connection on A/C unit and check condensation water drain for correct seating. Refer to=> [ Condensate Drain Hose, Checking ] Condensate Drain Hose, Checking.
- Reinstall removed components in reverse order of removal except driver storage compartment.
• When installing the instrument panel, make sure that the defrost intermediate piece its properly on A/C unit and the defrost vent does not pinch the intermediate piece.
• After installing the instrument panel, check the output direction and distribution of the air flow from the defroster vent to the windshield.
- Connect coolant hoses properly to heater core. Observe markings:
A Supply hose from cylinder head
B Return to the coolant pump
- Connect refrigerant lines to expansion valve. Refer to=> [ Expansion Valve Refrigerant Lines, Disconnecting and Connecting ] Expansion Valve Refrigerant Lines, Disconnecting and Connecting.
- Check installation position of coolant hoses to heater cores (they must not contact components which grow hot) and position and state of heat protection insulation applied to coolant hoses if necessary (not installed on all engine types).
- Bleed cooling circuit.
- Check coolant circuit for leaks, pay particular attention to the connection between coolant hoses and heater core. Refer to=> [ Heater Core ] Heater Core.
- Check grommet - C - in bulkhead for proper seating.
- Seal flange for coolant pipes to heater core - A - and for expansion valve (to evaporator) - B - at pass-through of grommet - C - with silicon adhesive sealant if necessary (to prevent water from penetrating).
- Evacuate and re-charge refrigerant circuit.
- Reinstall driver side storage compartment and remaining removed components.
- If necessary, check the A/C system using Vehicle diagnosis, testing and information system (VAS5051B) under "Guided Fault Finding".
- Check the air vent direction on vehicles with a manual climate control system. as depending on switch position, the flexible shaft rotates twice for one switch rotation via set of gears on heating & A/C unit and on heating & A/C unit controls. Refer to => [ Base Plate for Heater and A/C System Controls ] Base Plate For Heater and A/C System Controls.
- Operate the A/C system after filling the refrigerant circuit. Refer to=> [ A/C System, Operating After Filling Refrigerant Circuit ] Procedures.
• Note the information regarding operating the A/C system after filling.