GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the System Diagnostic Check?

--

Go to Step 2

Go to Diagnostic System Check

2

Inspect Fuse 4 in the fuse block.

Is Fuse 4 open?

--

Go to Step 3

Go to Step 4

3

Repair the short to ground in CKT 41 (BRN).

Is the repair complete?

--

Go to Step 15

--

4

  1. Disconnect the heater - A/C control connector C1.
  2. Place the ignition switch in the RUN position.
  3. Use a test lamp, connected to ground, to backprobe the heater - A/C control connector C1 terminal D.

Did the test lamp light?

--

Go to Step 6

Go to Step 5

5

Locate and repair a poor connection or an open in CKT 41 (BRN).

Is the repair complete?

--

Go to Step 15

--

6

  1. Reconnect the Heater - A/C control connector C1.
  2. Disconnect the blower motor connector.
  3. Place the ignition switch in the RUN position.
  4. Place the blower control switch in HI.
  5. Use a test lamp, connected to ground, to backprobe the blower motor connector terminal B .

Did the test lamp light?

--

Go to Step 12

Go to Step 7

7

  1. Remove the blower motor relay.
  2. Use a test lamp, connected to ground, to backprobe the blower motor relay harness connector terminal C2.

Did the test lamp light?

--

Go to Step 9

Go to Step 8

8

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

Is the repair complete?

--

Go to Step 15

--

9

Inspect circuit 65 (PPL) for a poor connection or an open.

Is there a poor connection or an open in the circuit?

--

Go to Step 10

Go to Step 11

10

Repair the fault in CKT 65 (PPL).

Is the repair complete?

--

Go to Step 15

--

11

Replace the blower motor relay.

Is the repair complete?

--

Go to Step 15

--

12

Keep the ignition switch in the RUN position and use a test lamp to backprobe between the blower motor connector terminal A and terminal B.

Did the test lamp light?

--

Go to Step 13

Go to Step 14

13

Replace the blower motor. Refer to Blower Motor and Fan Replacement .

Is the repair complete?

--

Go to Step 15

--

14

Locate and repair a poor or open connection in CKT 150 (BLK) between the blower motor connector terminal A and G205.

Is the repair complete?

--

Go to Step 15

--

15

Verify that the system operates properly.

Does the system operate properly?

--

System OK

Go to Step 2