A/C - Sudden Loss of Heat or Airflow
Group 64Heating and
Air Conditioning
Bulletin Number
64 02 93 3738
Woodcliff Lake, NJ
June 1993
Product Engineering
This Service Information bulletin supersedes S.I. 64 02 93 (3738) dated April 1993. This S.I. has a revised parts ordering procedure. Please remove and discard S.I. 64 02 93 (3738) dated April 1993 from your S.I. binder.
SUBJECT:
IHKR Sudden Loss of Heat or Airflow
MODELS:
E36
Situation:
The IHKR control module may occasionally stop responding to any of the temperature or airflow controls, unless the vehicle ignition is cycled off then back on.
Complaint:
In cold weather, the typical complaint is air temperature from the heater output dropping substantially. The output air temperature cannot be regulated with the control knob. Heat is only available at the maximum "override" position. Turning the ignition off, and restarting the vehicle corrects this condition. No faults are set in IHKR control module memory.
In warm weather, the typical complaint is the air flow diminishing to near zero from the center and instrument panel vents. Defroster (windshield) or footwell can be selected normally, but if the air distribution is set to face-level only, no airflow is present. The blower fan can be heard running, and appears to be working at all speeds, but the flaps for the face-level vents will not open. Turning the ignition off, and restarting the vehicle corrects this condition. No faults are set in IHKR control module memory.
Affected Vehicles:
E36 vehicles produced up to 11/92 are equipped with IHKR control module software version 10 (or earlier), and have potential for the complaints. The software version of the IHKR control module can be checked with the BMW Service Tester, the MoDiC or by visual examination of the control module label. Any software version 10 or earlier may be affected. The letters "SW 10" appear on the label of the latest E36 IHKR control modules that are potentially affected.
Correction:
In the case of customer complaints, replace the older software version IHKR control module with a newer, upgraded software version (e.g. "SW 16") IHKR control module (P/N 64 11 8 391 512).
Note:
Because of a change in coding to software version 16 IHKR control modules installed on an E36 vehicle equipped with an M50 engine, it may be necessary to code TWICE with the MoDiC and coding software version 6.021 or later. This is performed as follows: Install the control module. Code the module with the MoDiC and appropriate software. Turn the ignition OFF, and disconnect the black and white connectors from the IHKR control module. Reconnect the black and white connectors, turn the ignition ON, and code the module with the MoDiC a second time.
The extra coding step is not necessary on IHKR control modules with version 19 software (introduced approximately 3/93).
Parts Information:
E36 IHKR Control Module (Version 16 or later) 64 11 8 391 512
Warranty Status:
Parts and labor covered under the terms of the applicable BMW New Car Limited Warranty.
Defect Code: 64 11 90 42 00
Labor Operation: 00 50 129
Labor Allowance: 4 FRU