A/C Control Head - Locks Up/Clicking Noise

9217chevy03

GMC NUMBER: 91-1A-173

GROUP: 1A Heating and Ventilation

DATE: January 1991

CORPORATE
NUMBER: 161102


SUBJECT:
HVAC CONTROL HEAD LOCKS UP/TEMP DOOR ACTUATOR CLICKS WHEN AT FULL COLD (REP. CONTROL HEAD)

MODELS:
1991 C/K AND TOPKICK/KODIAK WITH A/C (RPO C60)


Owners of some 1991 C/K light duty trucks or 1991 C5H, C6H, or C7H medium duty trucks with the electronic pushbutton HVAC control head may experience a condition where the vent arrows on the left of the display and the temperature arrows on the bottom of the display begin flashing and the control head "locks up" so that no changes in the HVAC system can be made. This is caused when:
1. The control head is placed in defrost and the temperature arrow is placed at a point between full hot and full cold.
2. The "Heater" end of the selector button and the "Hot" end of the temperature scale button are pressed so that the mode actuator motor and the temperature door actuator motor are operating simultaneously.
Other 1991 C/K trucks may exhibit a clicking noise from the temperature door actuator, which is in the blower motor area. This is caused when the temperature is placed in full cold, and the temperature door actuator clicks for 45 seconds due to receiving pulses from the HVAC control head for the same 45 seconds.


Important

One truck will not experience both conditions.

To correct either of these conditions, replace the HVAC control head with a new HVAC control head (P/N 16152129 - LD or 16149268 - MD).


SERVICE PROCEDURE:
The procedure for replacement of the HVAC control head is found in section 1B "CONTROL ASSEMBLY REPLACEMENT" of the appropriate service manual.

SERVICE PARTS INFORMATION:

16152129 HVAC control 1991 C/K 1,2,3
head
16149268 HVAC control 1991 C5H, C6H,
head C7H

Parts are expected to be available on 1-13-92. In case of limited inventory, parts will be placed on 400 control to waive VIP surcharges. Only verifiable emergency orders will be accepted. SPO will make every effort to obtain parts. However, the part will be shipped premium transportation at the dealer's expense and all other order types will be placed on backorder until the 400 control is removed.

WARRANTY INFORMATION:
Labor Operation: D0362

Labor Time: 0.3 hrs.