Since working on the system is potentially dangerous, we strongly recommend that all work related to the air conditioning system be carried out by a BMW dealer or air conditioning specialist. At least don't remove any system components (hoses, compressor, fittings, etc.) until the system is completely discharged by a qualified technician. Read the precautions at the beginning of the Section Air Conditioner Maintenance and Precautions.
When installing a new compressor, the battery/dehydrator should also be replaced (see Section Removal and installation of the accumulator / dehydrator of the air conditioning system).
Withdrawal
1. Discharge the air conditioning system (see warning above).
2. Disconnect the negative battery cable.
If your car's radio is equipped with an anti-theft system, make sure you have entered the correct code before disconnecting the battery.
If, after connecting the battery, the inscriptions on the instrument panel appear in the wrong language, refer to Section Anti-theft audio system and instrument panel language, for instructions on how to set the desired language.
3. Disconnect the compressor clutch wiring.
4. Remove the drive belt (see chapter Car maintenance).
5. Disconnect the refrigeration lines from the rear of the compressor. Seal open lines to prevent moisture and dirt from entering.
6. Working under the vehicle, unbolt the compressor from the mounting brackets, lift it up and remove it from the vehicle.
Installation
1. When installing a new compressor, follow the instructions that came with it for draining excess oil before installing it.
2. The old clutch can be used on the new compressor.
3. Install in the reverse order of removal. All O-rings should be replaced with new ones specially made for use in air conditioning systems. Lubricate them with special oil before installation.
4. Have the system drained, charged, and leak tested by the same qualified person who discharged the system.