GM Service Manual Online
For 1990-2009 cars only

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The High speed blower motor control circuit is spliced to the Blower motor resistor circuit. A short to voltage on the control circuits will open the HVAC Blower fuse. Be sure to check all the blower motor control circuits for a short to ground.

  2. The ground circuit to be tested comes from the HVAC blower relay.

  3. Check the connection by removing and securely reinstalling before replacement of the HVAC control is considered.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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

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. Place the blower motor switch in each speed position.

Does the blower motor operate in any speed position?

Go to Blower Motor Malfunction

Go to Step 3

3

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

Does the test lamp illuminate?

Go to Step 7

Go to Step 4

4

Test the blower motor supply voltage circuit for an open, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 5

5

Test the High blower motor control circuit for an open, or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 6

6

Test the ground circuit of the HVAC control assembly for an open, short to voltage or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 8

7

Inspect for poor connections at the blower motor. 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 9

8

Inspect for poor connections at 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

Replace the blower motor. Refer to Blower Motor Replacement .

Did you complete the replacement?

Go to Step 11

--

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

--

11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2