A/C - Heater Temperature Drops During Extended Driving

Group 64: Heating and Air Conditioning
Bulletin Number: 64 12 93 (3936)

Woodcliff Lake, NJ
January 1994
Product Engineering

SUBJECT:
Drop in Heater Temperature during Extended Driving

MODELS:
E34 (10/91 - 7/93 production) with IHKR

Situation:
We have received a few E34 vehicle complaints that the passenger compartment starts to cool down, requiring adjustment with the rotary temperature control. This only seems to occur if the vehicle has been driven for an extended length of time.

Cause:
The interior temperature sensor fan may be sticking occasionally, causing the air around the sensor to remain stationary. On an extended drive, this lack of air movement may cause the temperature sensor to give a false reading higher than actual temperature. The heater continues to function, but at a slightly reduced temperature.

Correction:
In the case of a customer complaint on an E34 in the production range above, replace the interior temperature sensor blower.

Parts Information:
Improved motors for the sensor blower are available from Parts. The part number has been changed:

Description Part Number
E34 Temp Sensor Fan 67 32 8 361 479

Warranty Information:
Parts and labor covered under the terms of the applicable BMW New Car Limited Warranty.

Defect Code: 64 11 39 79 00
Labor Operation: 64 11 355 (Replace Temp Sensor Fan)
Labor Allowance: 6 FRU