GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: Air does not flow correctly from the air distribution outlets.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn OFF the HVAC controls.

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 each speed position?

Go to Step 4

Go to Blower Motor Inoperative

4

Does the blower motor operate at the desired speeds?

Go to Step 5

Go to Blower Motor Malfunction

5

  1. Place the blower motor switch in the maximum speed position.
  2. Alternately, place mode switch in the Max A/C and Vent positions.

Does the recirculation door move from the recirculation position to the ambient air position?

Go to Step 6

Go to Air Recirculation Malfunction

6

  1. Install a scan tool.
  2. Recalibrate the HVAC door actuators. Refer to Actuator Recalibration .
  3. With a scan tool, observe the current DTC list in HVAC Systems Automatic.

Does the scan tool display any DTCs?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 7

7

Place the mode switch in each mode position.

Does the air flow from the correct air distribution outlets in each selected mode position?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 8

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 .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

9

Inspect the air distribution system for the following conditions:

    • A restricted passenger compartment air filter
    • An obstruction restricting air flow
    • Air leaks
    • Misaligned ducts

Did you find and correct the condition?

Go to Step 11

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10

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3