Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 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 for Intermittent Conditions and Poor Connections in Wiring Systems.
Ensure that the panel vents are in the OPEN position for proper diagnosis.
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) Re-Calibrating Actuators (Auxiliary HVAC) .

Air Delivery Improper

Step	Action	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views
1	Did you perform the HVAC Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - HVAC Systems - Automatic
2	Turn ON the ignition, with the engine OFF. Place the blower motor switch in the OFF position. Is the blower motor OFF?	Go to Step 3	Go to Blower Motor Always On
3	Place the blower motor switch in each speed position. Does the blower motor operate in any of the speed positions?	Go to Step 4	Go to Blower Motor Inoperative
4	Does the blower motor operate in each speed position?	Go to Step 5	Go to Blower Motor Malfunction
5	With a scan tool, observe the Mode Switch parameter in the Heating and Air Conditioning data list. Activate the mode switch. Does the scan tool indicate that the Mode Switch parameter changes state?	Go to Step 6	Go to Step 8
6	Place the blower motor switch in the maximum speed position. Place the mode switch in the bi-level position. Place the recirculation switch in the ON position. Observe the drive shaft of the recirculation actuator. Place the recirculation switch in the OFF position. Does the recirculation door move from the recirculation position to the outside air position?	Go to Step 7	Go to Air Recirculation Malfunction
7	Place the mode switch in the floor position. Turn ON the auxiliary HVAC control module. Place the auxiliary mode switch in the vent position. Observe the airflow from the auxiliary outlets. Place the front mode switch in the defrost position. Does air flow from the auxiliary outlets?	Go to Air Delivery Improper - Auxiliary (VIN 6 excluding Envoy XUV) or Air Delivery Improper - Auxiliary (VIN 3 including Envoy XUV)	Go to Diagnostic Aids
8	Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 10	Go to Step 9
9	Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement?	Go to Step 10	-
10	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2