A/C Vents - Clicking Noises
GROUP 64Heating and Air Conditioning
Bulletin Number
64 04 98
Woodcliff Lake, NJ
August 1998
Product Engineering
SUBJECT:
Air Stratification Stepper Motors Noisy in E38 Vehicles
MODEL:
7 Series (E38) produced up to May of 1998
Complaint:
Clicking noise can be heard from the area of the center vents during driving. The noise is especially pronounced when the stratified air wheel is adjusted (radio is turned off and blower speed is selected to low setting).
Cause:
The stepper motors for air stratification are activated too frequently due to incorrect IHKA programming.
Correction:
On a customer complaint basis only, replace the IHKA Control Module with one incorporating improved software (version SW 13.0) for stepper motor activation (P/N 64 11 8 385 592), and also replace the two stratification stepper motors (P/N 64 11 8 391 378 and P/N 64118391377).
The improved IHKA Control Modules were phased into series production in May of 1998.
Note:
The IHKA control module must be ordered using the last 7 digits of the VIN as the purchase order number.
Due to limited supply, you should not use these control modules for the stocking purposes.
Procedure:
The two stratification stepper motors are located behind the center air grill, on top of the heater box, towards the front of the vehicle (see illustration).
Location of two stratification stepper motors.
In order to gain access to the stratification stepper motors, the following components should be removed:
1. Instrument panel (for replacement procedure refer to Repair Instruction 62 21 000)
2. Upper fresh air grill (refer to Repair Instruction 64 22 161)
3. Center fresh air grill (refer to Repair Instruction 64 22 161)
4. Radio and MID (refer to Repair Instruction 65 11 030), or Board Monitor (refer to Repair Instruction 65 52 510)
5. Passenger airbag cover
Remove the following components:
1. Instrument panel
2. Upper air grill
3. Center air grill
4. Radio and MID/Board Monitor
5. Passenger airbag cover
Installation Hints:
Location of two stepper motors for center vents
1. Before replacing the stratification stepper motors, remove the two stepper motors for the center vents which are located in the same mounting brackets, towards the rear of the vehicle.
Operating range of stepper motor actuating arm
2. In order to disengage the stratification stepper motor from the bracket, the motor's actuating arm must be positioned in the middle of its operating range. The position of the actuating arm can be changed by electrically reconnecting the stratification wheel control (center vent assembly), and white observing the stepper motor actuating arm, adjusting the stratification wheel and temperature setting on the IHKA, until the arm reaches its middle position.
Parts Information:
Warranty Information:
Covered under the terms of the BMW New Car Limited Warranty.