GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Inspect the fuse block for an open in the HVAC HI fuse.

Is the HVAC HI fuse open?

--

Go to Step 2

Go to Step 5

2

  1. Disconnect the blower motor resistor.
  2. Use a test lamp to probe between the blower motor resistor harness connector terminal G (CKT 40) to ground.

Does the test lamp light ?

--

Go to Step 4

Go to Step 3

3

Locate and repair a short to ground in CKT 40 (ORN).

Is the repair complete?

--

Go to Step 9

--

4

  1. Turn the ignition switch to the RUN position.
  2. Place the heater-A/C control in the VENT position.
  3. Place the blower switch in the HI position.
  4. Use a test lamp to probe between the blower motor resistor harness connector terminal F (CKT 52) and ground.

Does the test lamp light ?

--

Go to Step 5

Go to Step 6

5

Replace the blower motor resistor. Refer to Blower Motor Resistor Replacement .

Is the repair complete?

--

Go to Step 9

--

6

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the heater-A/C control connector C 1.
  3. Use a Digital Multi Meter (DMM) to test for an open, excessive resistance or a short to ground in CKT 52 (ORN) between the heater-A/C control harness connector C 1 terminal C and the blower motor resistor harness connector terminal F.

Is there an open or short to ground in CKT 52 (ORN)?

--

Go to Step 7

Go to Step 8

7

Locate and repair the open or the short to ground in CKT 52 (ORN).

Is the repair complete?

--

Go to Step 9

--

8

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

Is the repair complete?

--

Go to Step 9

--

9

Verify that the system operates properly.

Does the system operate properly?

--

System OK

Go to Symptoms