Removal and Replacement
A/C Unit
Special tools, testers and auxiliary items required
• Hose clamps up to 25 mm diameter (3094)
• Standard compressed air gun with rubber nozzle
Preparing for Removal
- Switch off ignition.
- Remove the air intake unit, refer to => [ Air Intake Unit ] Air Intake Unit.
CAUTION!
There is a risk of scalding from hot steam and coolant.
• The refrigerant system is under pressure when the engine is warm.
• To reduce the pressure, cover the coolant reservoir cap with cloths and open it carefully.
- Open the coolant reservoir cap.
- Remove the center tunnel cover - 1 -.
- Remove the driveshaft.
CAUTION!
There is a risk of burns.
• The heat regulating valve unit may be warn or hot even when the engine is cold because it is continuously activated when the ignition is on depending on the temperature setting on the Climatronic Control Module (J255).
- Clamp off the coolant supply hose - A - to the heat regulating valve unit - B - and the coolant hose - C - from the central heat exchanger return - D - with hose clamps (3094).
- Remove the coolant hoses - A and C -.
- Connect a hose to each heat regulating valve unit (to the extension) and to the heat exchanger central return.
- Place a reservoir - F - under the hose - E -.
- Place the compressed air gun - A - (with rubber nozzle) on the hose - B -.
- Carefully blow the coolant out of the heat exchangers via the return line by pressing the coolant hoses - C and D - together.
- Seal the central return line with a sealing plug.
- Remove instrument panel.
- Remove the bolt - A - and the footwell vent air channel - B -.
- Remove the bolt - B - and the footwell vent air channel - A -.
- Remove the central tube.
- Remove the refrigerant line from the connection to the A/C unit, refer to => [ A/C Unit and Refrigerant Lines ] Refrigerant Circuit.
- Cover the floor mat in the center tunnel area at the left and right under the heat exchanger with a waterproof cover and absorbent paper.
- Remove the bolt - H - on the coolant line connection - G -.
- Remove the coolant line connection on the coolant lines to the heat exchanger.
- Loosen the bolts - A, C and F - several turns so the coolant lines can move in the brackets - B, D and E -.
Removal
• On removal, note down bolt lengths and assignment for installation later.
• All cable ties and other wiring harness fasteners released or cut open on removing air conditioner unit are to be re-attached in same position on installation.
- Fold the floor covering back carefully until the condensation water drain hose - B - is visible.
- Cover the floor mat area under the condensation water drain hose with absorbent paper (so that any water present does not flow onto or below the floor mat).
- Remove the condensation water drain hose - B - on the A/C unit - A - and the rubber lip - C - on the center tunnel - D -.
- Remove the condensation water drain hose.
- Repeat the procedure on the opposite side.
- Remove the A/C unit from the vehicle interior.
Installing
Installation is done is reverse order, observe the following:
• When guiding the A/C unit in, be careful of the lines to the control motors and the seals. They must not be pinched or damaged.
• Check all seals and replace them if necessary.
- Insert the A/C unit.
- Install the central tube.
- Install the refrigerant line on the connection to the A/C unit, refer to => [ A/C Unit and Refrigerant Lines ] Refrigerant Circuit.
- Connect the coolant line connection to the coolant lines to the heat exchanger and fill the coolant circuit, refer to => [ Replace the seals on
the coolant lines. ] A/C Unit Heat Exchanger.
- Evacuate and fill refrigerant circuit.
- Check the refrigerant line connection points for leaks, e.g. using an electronic leak detector.
- Install the instrument panel.
- Install the air intake unit, refer to => [ Air Intake Unit ] Air Intake Unit.
- Install the driveshaft.
- Install the center tunnel cover.
After finishing the repairs, perform the following work on the Climatronic Control Module (J255) using Vehicle diagnosis, testing and information system VAS 5051/ in the "Guided Fault Finding" function:
- Check the DTC memory and erase any malfunctions shown.
- Perform the basic setting.
- Perform the output diagnostic test mode.
- Operate the A/C system after filling the refrigerant circuit, refer to => [ Operating After Filling Refrigerant Circuit ] Heating, Ventilation & Air Conditioning.
• Note the information regarding operating the A/C system after filling.