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?

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Go to Step 2

Go to Symptoms

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the rear air conditioning (A/C) switch in the MED position.
  3. Using a test lamp backprobe from the rear A/C resistor pack CKT 1072 (LT BLU) cavity A to ground.

Does the test lamp illuminate?

--

Go to Step 3

Go to Step 4

3

Inspect for a poor connection at the rear A/C resistor pack.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does a poor connection exist?

--

Go to Step 9

Go to Step 5

4

Using a test lamp backprobe from the rear A/C switch CKT 1072 (LT BLU) cavity B to ground.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 7

5

Replace the rear A/C resistor pack.

Refer to Auxiliary Blower Motor Resistor Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

--

Go to Step 10

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6

Repair the open in CKT 1072 (LT BLU).

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

--

7

Inspect for a poor connection at the rear A/C switch.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find a poor connection?

--

Go to Step 9

Go to Step 8

8

Replace the rear A/C switch. Refer to Control Switch Replacement - Auxiliary in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

--

Go to Step 10

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9

Repair the poor connection.

Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2