GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics or HVAC Vacuum Schematics

Connector End View Reference: HVAC Connector End Views

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

1

Did you review the HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

  1. Turn ON the ignition, with the engine OFF.
  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 correctly for each speed position?

Go to Step 5

Go to Blower Motor Malfunction

5

Test the Ignition 3 voltage circuit of the vacuum pump assembly for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Test the ground circuit of the vacuum pump assembly for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 7

7

Disconnect the vacuum hose going to the vacuum pump.

Does the vacuum pump turn ON?

Go to Vacuum Control System Diagnostic

Go to Step 8

8

Inspect for poor connections at the harness connector of the vacuum pump assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

9

Replace the vacuum pump assembly. Refer to Vacuum Pump Assembly 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 1