Air Door: Description and Operation

Programmer:

AIR-MIX DOOR LINKAGE
The air-mix door linkage consists of a plastic crank arm integral with the output shaft of the programmer motor, a serrated nylon retainer, and a threaded rod. One end of the rod is fastened to the air-mix door and the opposite end is retained by the serrations in the nylon retainer. The programmer positions the air-mix door by this rod when the Body Control Module (BCM) sends the appropriate data signal.

AIR MIX DOOR POSITION
The proper air mix door position is determined by the BCM. In order to provide the proper mix of warm and cool air, the BCM monitors the following variables:
- Outside temperature
- Low side temperature
- Coolant temperature

Based upon these inputs the BCM can position the air mix door for the appropriate blend of air through the evaporator core and heater core depending upon the current program number. By monitoring a feedback potentiometer on the programmer dc motor, the BCM commands the programmer to move the door until the desired position is achieved.