1990 Corvette: Service Bulletin: Loss of Heating or Cooling Control
Subject: Loss of Heating or Cooling Control - New Programmer
Model and Year: 1990 CORVETTE
Source: Chevrolet Service Bulletin
Bulletin Number: 90-378-1A - (10/25/1990)
TO: ALL CHEVROLET DEALERS
The customer may comment on a loss of heating or cooling control. The temperature of air coming from the HVAC system cannot be changed. A code 01 or 02 may also be set in the HVAC control head. The "auto" blower may read "O" speed
The air mix door of the HVAC system will not move out of the full hot or full cold position, causing loss of heating or cooling control because the mix motor has failed to recalibrate itself.
This condition may be caused by wiring disconnects, air mix door motor condition, Freon loss, or related A/C system problems. If normal diagnostic procedures do not correct this condition, a revised A/C programmer is available.
Part Number Engine
16155285 L98 (VIN Code 8)
16155286 LT5 (VIN Code J)
Use the procedure in Section 1C1 of the 1990 Service Manual to replace the programmer.
If a DELCO-LOC 11 security code has been programmed originally into the radio by the customer, the radio may display "LOC" when the battery cable is disconnected. If this condition occurs, the customer will have to re-enter his/her security code to turn on the radio. Refer to Section 9A in the Service Manual for further information on this procedure.
NOTICE: WHILE WORKING ON THE HVAC SYSTEM, DO NOT RUN THE AIR MIX DOOR MOTOR WHEN IT IS REMOVED FROM THE HEATER CASE. THIS WILL DAMAGE THE MOTOR.