GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

1

Did you review the Air Delivery Description and Operation and the Air Temperature Description and Operation perform the necessary inspections?

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2

Operate the blower motor at each speed.

Does the blower motor operate when turned to the OFF position?

Go to Step 3

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

3

Remove the HTR relay from fuse and relay block 3.

Does the blower motor run?

Go to Step 4

Go to Step 5

4

Repair the short to voltage in the blower motor supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

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5

Test that the HTR relay is open between terminals 4 and 5 and that there is continuity between terminals 4 and 2. Refer to Power and Grounding Component Views in Wiring Systems.

Did the relay test OK?

Go to Step 6

Go to Step 7

6

Test the HTR relay control circuit for a short to ground. 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 heater relay.

Did you complete the replacement?

Go to Step 9

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8

Replace the blower switch. Refer to Blower Switch Replacement .

Did you complete the replacement?

Go to Step 9

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9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3