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 HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2

  1. Start the engine.
  2. 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 at all?

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

  1. Place the headlamp switch in the PARK position.
  2. Place the instrument panel dimmer switch in the brightest position.
  3. Place the mode switch in the vent position.
  4. Place the blower motor switch in the maximum speed position.
  5. Place the outside air switch in the ON position.
  6. Place the recirculation switch in the ON position.

Does the recirculation door operate properly?

Go to Step 6

Go to Air Recirculation Malfunction

6

Place the mode switch in the defrost position.

Does the recirculation door move to the outside air position?

Go to Step 7

Go to Step 8

7

Place the mode switch in each mode position.

Is the airflow sufficient from the correct outlets in each mode?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Vacuum Control System Diagnostic

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

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2