Heater - Low Heat Delivery

Bulletin Number: 91-1-12
Reference Number: 131104
Publish Date: 9/91


Subject: REVISED PROCEDURE FOR LOW HEAT DELIVERY RELATED DIAGNOSIS (ENHANCED TEMPERATURE CONTROL CABLE ADJUSTMENT)

Models
Affected: 1989-91 SUNBIRD AND GRAND AM MODELS

On customer comments of low heater output on 1989-91 Sunbird and Grand Am models, before replacing a suspected defective engine cooling thermostat, proper diagnosis of the condition must be performed to avoid the possibility of a repeat repair. Follow "Diagnosis" as shown in Section 1A/lB of the appropriate Service Manual.

After completing the diagnosis, use the following as a guide to the next corrective step:

* If the diagnosis indicates a defective thermostat, refer to Section 6C for replacement.

* If the diagnosis indicates a defective temperature control cable, refer to Section 1A/lB for replacement.

* If the diagnosis indicates the temperature control cable is no longer "snapped" into its retainer, refer to "Temperature Control Cable Repair" in the 1991 Service Manual, Sections 1A/1B.

* If the diagnosis indicates that the temperature control cable is out of adjustment, refer to the following procedure to repair.





TEMPERATURE CONTROL CABLE ADJUSTMENT PROCEDURE

Condition: 1. "Spring back" off full "hot" temperature control position (or not attaining full "cold" temperature door position).

Condition: 2. "Spring back" off full "cold" temperature control position (or not attaining full "hot" temperature door position).


Cause: The temperature control cable "clip" needs adjustment. Refer to the illustration for correct gripping of the "clip" during adjustment.

Correction:

For Number: 1. Grip "clip" at module end of cable while pulling temperature control lever to "hot" position.

Correction:

For Number: 2. Grip "clip" at module end of cable while pushing temperature control lever to "cold" position.

NOTICE: FAILURE TO GRIP "CLIP" CORRECTLY WILL DAMAGE ITS ABILITY
TO HOLD POSITION ON THE CABLE. THE TEMPERATURE CONTROL
CABLE MUST BE REPLACED IF "CLIP" RETENTION FAILS.

Verify correct adjustment after repair by observing for no, or very little, "spring back" of the temperature control lever and listening for temperature door "slam" when the control lever is moved to full hot and cold positions quickly.

Please note your copies of the Service Manuals in Sections 1A and 1B, under "Temperature Control Cable", with these new adjustment instructions.


Warranty and Labor Information:

Use the appropriate failure code for each occurrence.

For thermostat or temperature control cable replacement, use current applicable warranty and labor information.

For temperature cable repair at the heater control, use current heater warranty and labor information.

For temperature control repair at the HVAC module or cable adjustment:

Labor Operation Number : D0400

Labor Time: Sunbird .2 Hr.
Grand Am .2 Hr.