Diagnostic Aids

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The condition may be intermittent. Refer to TESTING WIRING SYSTEMS FOR INTERMITTENT & POOR CONNECTIONS in Wiring Systems.
Inspect the air delivery system for the following conditions:
- An obstruction to the airflow
- Air leaks
- Misaligned air ducts
- Broken or binding linkages or doors
If the scan tool indicates that the Door Actual parameter is 5-10 counts from the Commanded Door parameter, then perform the recalibration procedure for the HVAC door actuators. Refer to Re-Calibrating Actuators (Primary) or Re-Calibrating Actuators (Auxiliary HVAC) .

Fig 1: Diagnostic System Check - Air Delivery Improper

Courtesy of GENERAL MOTORS CORP.