ATC - Revised Calibration Procedure

NO.: 24-17-93 Rev. A

GROUP: Heating & A/C

DATE: Aug. 13, 1993

SUBJECT:
ATC Calibration Procedure

NOTE:
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN NO. 24-17-93 WHICH SHOULD BE REMOVED FROM YOUR FILES. A REVISED PROCEDURE HAS BEEN ADDED.

MODELS:

1993 (LH) Concorde/Intrepid/Vision
1994 (LH) LHS/New Yorker/Concorde/Intrepid/Vision

DISCUSSION:

The ATC system must be re-calibrated each and every time the power is disconnected at the body controller, M1 (battery) fuse, or at the battery. Failure to properly calibrate the ATC system will cause the blend air door to oscillate between hot and cold, causing temperature shifts at the outlets and/or the blower motor to sound as if it is varying from a low to a high speed. These conditions will typically occur when the engine compartment is cool.

The normal ATC calibration procedure in the Service Manual (Publication No. 81-270-3140) Page 24-21 is to set the temperature to 75 degrees F, and simultaneously press the floor, mix, and defrost buttons until the display starts to blink. During this procedure, the engine has to be running to ensure proper system voltage (14.5 volts) and calibration. However, the engine running will not always guarantee 14.5 volts.

A revised procedure has been developed to get the necessary 14.5 volts. THE ATC CANNOT BE CALIBRATED PROPERLY WITH LESS THAN 14.5 VOLTS. To maintain 14.5 volts during calibration, it will be necessary to:

^ Connect a battery charger to vehicle and adjust rate to maintain 14.5 volts.

^ Monitor voltage using the DRBII or volt meter at the battery (do not exceed 14.7 volts).

^ Perform calibration procedure with the KEY ON, ENGINE NOT RUNNING.

NOTE:
UPON COMPLETION OF THE CALIBRATION, IF ANY DIAGNOSTIC TROUBLE CODES ARE DISPLAYED, REFER TO THE 1993 LH BODY DIAGNOSTIC MANUAL (PUBLICATION NO. 81-699-0317) FOR REPAIR PROCEDURES.

POLICY: Information Only.