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 heat switch in the HIGH position.
  3. Using a test lamp backprobe from the rear heater switch CKT 1924 (WHT) cavity A to ground.

Does the test lamp illuminate?

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Go to Step 3

Go to Step 4

3

Repair the open in CKT 1924 (WHT).

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 7

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4

Inspect for a poor connection at the rear heater switch.

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

Did you find a poor connection?

--

Go to Step 6

Go to Step 5

5

Replace the rear heater switch.

Refer to Control Switch Replacement - Auxiliary in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

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Go to Step 7

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6

Repair the poor connection.

Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2