GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the heater-A/C Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Place the heater A/C mode control in the VENT position.
  2. Place the blower control in the HI position.
  3. Use a test lamp connected to B+ in order to test for a short to ground on circuit 706 (LT BLU) at the heater-A/C harness connector terminal 4.

Does the test lamp light?

--

Go to Step 4

Go to Step 3

3

  1. Reconnect the heater-A/C control harness connector.
  2. Use a test lamp connected to B+ in order to test for a short to ground on circuit 706 (LT BLU) between the vacuum/electric harness connector terminal 4 and the heater-A/C control connector C2, terminal A7.

Does the test lamp light?

--

Go to Step 5

Go to Step 6

4

Locate and repair a short to ground on circuit 706 (LT BLU). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 7

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5

Replace the vacuum/electric solenoid module. Refer to Vacuum Electrical Solenoid Replacement .

Is the repair complete?

--

Go to Step 7

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6

Replace the heater-A/C control module. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Step 7

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7

Verify that the system operates properly.

Does the system operate properly?

--

System OK

Go to Diagnostic System Check