Symptom Diagnostic Charts

In certain cars with rear A/C, within the chassis number ranges given below, noise can be heard from the air vent in the parcel shelf. This noise arises when pressure pulses from the compressor are transmitted to the A/C pipes under the car when the solenoid valve in the rear A/C unit is closed. This means that the noise is more noticeable when the rear A/C unit is not on.

In order to remedy this, an adapter harness, part No. 44 18 372, has been developed. The function of the adapter harness is to keep the solenoid valve open, even when the rear A/C unit is not on.
In a number of cars, the wrong adapter harness has been installed. The resistor in this adapter harness is too small, which means that the rear A/C unit does not work.

This applies to all 9000 CD cars with rear A/C between the following chassis numbers:
N1000001 - N1020439

Action
Install, or change, the adapter harness on all affected cars at the next service.
1 Remove the backrest.
2 Install or change the adapter harness between the car's wiring harness and the rear A/C unit's internal wiring harness.
The adapter harness should be positioned so that it becomes a part of the rear A/C unit's internal wiring harness.
3 Reinstall the backrest.

Materials
Adapter harness part No. 44 18 372