GM Service Manual Online
For 1990-2009 cars only

Test Description

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

  1. Test the Low, Med 1, Med 2 and High blower motor control circuits for an short to ground. The High speed blower motor control circuit is spliced to the Blower motor resistor circuit. This circuit should be checked for a short to ground also.

  2. 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 ON while the blower motor switch is in the OFF position.

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

  1. Turn OFF the ignition.
  2. Disconnect the HVAC control assembly connector.
  3. Turn ON the ignition, with the engine OFF.

Is the blower motor OFF?

Go to Step 5

Go to Step 4

4

Repair the applicable blower motor control circuit for an short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 7

--

5

Inspect for poor connections at the harness connector of 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 7

Go to Step 6

6

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2