Special tools and workshop equipment required

• Hose clamps, up to 25 mm - 3094-
• Engine bung set - VAS 6122-
• Commercially available compressed-air gun

Removal:

• Turn off the ignition and all electricity consumers.

Vehicles without access and start authorisation system

• Remove ignition key, if fitted.

Vehicles with access and start authorisation system

• Store ignition key outside the vehicle to prevent the ignition from being switched on unintentionally.

Continued for all vehicles

• Disconnect battery.

Open cap -arrow- on coolant expansion tank.

Vehicles with air conditioner

• Extract refrigerant.
• Detaching refrigerant pipe with internal heat exchanger from mount on the expansion valve.

Continue for all vehicles

• Mark installation position of coolant hoses -1- and -4-.

Note The heat exchanger is designed for a certain coolant flow direction.

The coolant hoses must therefore be connected on the correct sides.

• Pinch off the coolant hoses with hose clamps -3094- .
• Lift the fasteners -2, 3- and detach the coolant hoses from the heating system heat exchanger.

• Fit a short hose -A- to the upper connection.
• Insert the compressed air gun in the end of the hose.
• Hold a collector -B- under the lower connection -C- and use the compressed air gun to carefully blow the coolant out of the heat exchanger.
• Seal open lines and connections with clean plugs from the Engine sealing plug set - VAS 6122- .

Remove dash panel.

• Remove the rear footwell vent.
• If fitted: Remove the rear vent air duct .
• Unplug the connector -3- at the fresh air blower -1-.
• Place absorbent paper over the floor covering beneath the heater and air conditioning unit.

• Detach the condensation drain -2- from the heater and air conditioning unit -1-.
• Lay bare the duct -3-.

• Lay bare the wiring harness -2- at the mounts -4- -arrows-.

Note Do not remove the carrier for the onboard supply control unit - J519- and associated components: Onboard supply control unit - J519- , fuse boxC-SC-, control unit for parking aid - J446- , warning buzzer for front parking aid - H22- . The components mentioned may differ from one another depending on the vehicle fittings.

• Remove dash panel cross member.
• Unscrew the threaded locating pin on the left side of the cross member.
• Displace the dash panel cross member towards the back.
• Remove the heating and air conditioning unit -1- to right.

Installing

Install in reverse order of removal; note the following.

• Fill coolant.
• Vehicles with climate control: Fill refrigerant and refrigerant oil.