GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you review the HVAC operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

2

  1. Turn the mode switch to the OFF position.
  2. Disconnect connector C2 of the heater and A/C control module.
  3. Turn ON the ignition, with the engine OFF.

Does the blower motor continue to run?

--

Go to Step 3

Go to Step 4

3

Remove the FRONT HVAC fuse.

Does the blower motor continue to run?

--

Go to Step 5

Go to Step  6

4

Inspect for a short to voltage on CKT 119 (WHT).

Refer to Circuit Testing in Wiring Systems.

Did you find short to voltage?

--

Go to Step 10

Go to Step 9

5

  1. Disconnect the blower motor resistor and relay pack.
  2. Using a test lamp check for voltage on CKT 60 (YEL), CKT 63 (TAN) and CKT 72 (LT BLU).

Did you find voltage on any circuit.

--

Go to Step 7

Go to Step 8

6

Inspect for a short to voltage on CKT 340 (ORN).

Refer to Circuit Testing in Wiring Systems.

Did you find a short to voltage?

--

Go to Step 11

Go to Step 12

7

Repair the short to voltage on the affected circuit.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

8

Repair the short to voltage on CKT 65 (PPL).

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

9

Replace the heater and A/C control module. Refer to Control Assembly Replacement in Heater, Ventilation, and Air Conditioning.

Did you complete the replacement?

--

Go to Step 13

--

10

Repair the short to voltage on CKT 119 (WHT).

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

11

Repair the short to voltage on CKT 340 (ORN).

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 13

--

12

Replace the resistor and relay pack. Refer to Blower Motor Resistor Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the repair?

--

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2