A/C - IHKA Blows Too Hot In Below Freezing Temperatures
SI B64 05 02Heating and Air Conditioning
March 2003
Service Engineering
This Service Information bulletins supersedes S.I. B64 05 02 dated January 2002.
[NEW] designates changes to this revision
SUBJECT
IHKA Blows Too Hot at Temperatures Below 32°F
MODEL
E46 (3 Series) excluding convertible, vehicles from 04/02 to 12/02
For E46 convertible, refer to SI B61 04 03
SITUATION
At ambient temperatures below 0°C (32°F), the IHKA heats at maximum capacity, and doesn't regulate temperature. Customers complain that the car gets too hot.
CAUSE
The instrument cluster (SW 31.0, 32.0) sends an incorrect ambient temperature over the K-bus. At 0°C, the K-bus signal is -45°C.
Note:
The IHKA coding fix (described below) was introduced in series production 12/16/02. A revised Instrument Cluster (5W34), which corrects the K-bus signal will be introduced in series production mid February 2003.
CORRECTION
On a customer complaint basis, and using DISPlus/GT1, recode the IHKA using DIS CD32, update # 1, or later.
Do not replace parts
Note 1) It is not necessary to recode the instrument cluster.
Note 2) The new coding reconfigures the IHKA so that the temperature signal below 0°C is ignored.
Even after recoding and when using the DISPlus/GT1, at ambient temperatures below 0°C the temperature signal on the K-bus will be seen as -45°C.
Note 3) The ambient temperature as displayed on the Instrument Cluster is not affected by this problem. The temperature is displayed correctly.
[NEW] WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty.