GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

DEFINITION: The blower motor is ON while the HVAC controls is in the OFF position.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn OFF the HVAC controls.

Does the blower motor operate?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

With the scan tool observe the Commanded Blower parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Commanded Blower parameter is near the specified value?

0%

Go to Step 4

Go to Step 6

4

Disconnect the HVAC control module.

Does the blower motor continue to operate?

--

Go to Step 5

Go to Step 6

5

  1. Inspect the housing of the blower motor for a short to ground.
  2. Inspect for poor connections at the harness connector of the blower motor control processor. Refer to Wiring Repairs and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8

7

Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement .

Did you complete the replacement?

--

Go to Step 9

--

8

Replace the HVAC control module. Refer to HVAC Control Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2