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: The blower motor is ON while the blower motor switch is in the OFF position or blower motor is ON when the ignition is OFF.

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 the OFF position.

Is the blower motor OFF?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Disconnect the HVAC relay.

Does the blower motor turn OFF?

Go to Step 7

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the blower motor resistor assembly.
  3. Turn ON the ignition, with the engine OFF.

Is the blower motor OFF?

Go to Step 5

Go to Step 6

5

Test the Low, Med 1, and the Med 2 blower motor control circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 8

6

Disconnect the HVAC control assembly.

Is the blower motor OFF?

Go to Step 8

Go to Step 7

7

Repair the short to ground in the blower motor high control circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 11

--

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 .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

9

Replace the ignition 3 relay.

Did you complete the replacement?

Go to Step 11

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10

Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2