A/C - Auto Temp Control Reverts To Manual Mode

NO: 24-06-98

GROUP: Air Conditioning

DATE: May 22, 1998

SUBJECT:

Automatic Temperature
Control, Un-Requested
Change to Manual

MODELS:

1998 - 1999 (LH) Concorde/Intrepid/LHS/300M

NOTE:
THIS BULLETIN APPLIES VEHICLES BUILT BEFORE JULY 20, 1998 (MDH 0720XX). THE LAST SIX DIGITS OF THE V.I.N. WILL BE IN THE ONE HUNDRED THOUSAND SERIES (1XXXXX).

DISCUSSION:

The Automatic Temperature Control (ATC) system, if left in "AUTO" mode when the ignition is turned off, occasionally reverts to "MANUAL" mode when the ignition is turned back on. The following conditions will cause this to happen:

1. Removal of the ATC head while servicing the A/C or radio, without disconnecting the battery, will set an erroneous Diagnostic Trouble Code (DTC), "IN CAR TEMPERATURE SENSOR FAILURE" in the Body Control Module (BCM). The presence of this DTC will result in the un-requested "AUTO" to "MANUAL" change.

2. Changing the blower speed while the ignition is turned off will result in the unrequested "AUTO" to "MANUAL" change.

Condition # 1 can be prevented by DISCONNECTING THE BATTERY DURING ELECTRICAL SYSTEM SERVICE, and corrected by erasing the DTC.

Condition # 2 is normal operation of the ATC and should be explained to the owner as such.

POLICY: Information Only