GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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 in any of the speed positions?

Go to Step 4

Go to Blower Motor Inoperative

4

Does the blower motor operate in the desired speed[s]?

Go to Step 5

Go to Blower Motor Malfunction

5

  1. Place the mode switch in the vent position.
  2. Place the blower motor switch in the maximum speed position?
  3. Place the outside air switch in the ON position.
  4. Place the recirculation switch in the ON position.

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

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.

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

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 assembly. 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 assembly. Refer to Heater and Air Conditioning Control 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