GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The auxiliary blower motor is inoperative in all speed positions.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

Place the auxiliary blower motor switch in all speed positions.

Is the auxiliary blower motor inoperative in all speed positions?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

  1. Turn the ignition OFF.
  2. Disconnect the auxiliary blower motor.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the auxiliary blower motor supply voltage circuit and the high speed blower motor control circuit.
  5. Place the blower motor switch in the maximum speed position.

Does the test lamp light?

Go to Step 9

Go to Step 4

4

Connect a test lamp between the auxiliary blower motor supply voltage circuit and ground.

Does the test lamp light?

Go to Step 6

Go to Step 5

5

Repair the battery positive voltage circuit of the auxiliary blower motor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 12

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6

Test the high speed auxiliary blower motor control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition

Go to Step 12

Go to Step 7

7

Test the ground circuit of the auxiliary blower motor switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the auxiliary blower motor switch. 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 12

Go to Step 10

9

Inspect for poor connections at the blower motor. 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 12

Go to Step 11

10

Replace the auxiliary blower motor switch. Refer to Auxiliary Blower Motor Switch Replacement .

Go to Step 12

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11

Replace the auxiliary blower motor. Refer to Auxiliary Blower Motor Replacement in Heating Ventilation and Air Conditioning.

Did you complete the replacement?

Go to Step 12

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12

Operate the system in order to verify the repair.

Did you correct the condition?

Go to Step 2

System OK