GM Service Manual Online
For 1990-2009 cars only

Test Description

The number below refers to the step number on the diagnostic table.

  1. The blower motor parameter must be commanded ON before an OFF command will function.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The blower motor operates with the HVAC controls 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 the ignition ON, with the engine OFF.
  2. Turn OFF the HVAC controls.

Is the blower motor OFF?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

With a scan tool observe the Blower Motor Speed Command parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the Blower Motor PWM Speed parameter is near the specified value?

0%

Go to Step 4

Go to Step 6

4

  1. With a scan tool, command the Blower Motor parameter ON in the Heating and Air Conditioning Scan Tool Output Controls.
  2. Command the Blower Motor parameter OFF.

Does the blower motor turn OFF?

--

Go to Step 6

Go to Step 5

5

Inspect for poor connections at the harness connector of the blower motor control processor. Refer to Wiring Repairs and Connector Repairs .

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 .

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 Module Replacement .

Did you complete the replacement?

--

Go to Step 9

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8

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

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