Circuit Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The air temperature actuator is an electronic device that incorporates a stepper motor and a feedback potentiometer. The HVAC control module determines the position of the air temperature actuator from the voltage on the potentiometer. When the air temperature changes by greater than 4 counts, the control module performs the following functions:

Drives the air temperature actuator in the appropriate direction in order to achieve the desired setting
Compares the actual position to the commanded position

If the actual value differs from the commanded value by 4 or more counts, the actuator is stalled, and the DTC will set.