GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Inspect the DIC/HVAC fuse in the fuse block to see if it is open.

Is the DIC/HVAC fuse open?

--

Go to Step 2

Go to Step 3

2

Locate and repair a short to ground in circuit 541 (BRN).

Is the repair complete?

--

Go To Step 18

--

3

  1. Place the ignition switch in the RUN position.
  2. Use a Digital Multimeter (DMM) to backprobe between the heater-A/C control harness connector C 2 terminal G (circuit 733) and ground.
  3. Move the temperature control knob from WARM to COOL and COOL to WARM.

Does the measured voltage vary within the specified value?

1-12 V

Go to Step 4

Go to Step  5

4

  1. Disconnect the LH electric actuator connector.
  2. Connect a DMM from the LH electric actuator harness connector terminal 10 (circuit 541) and ground.

Is the measured voltage within the specified value?

9-14 V

Go to Step 6

Go to Step  7

5

  1. Disconnect the heater-A/C control harness connector C 2.
  2. Connect a DMM, between the heater-A/C control connector C 2 terminal C (circuit 541) and ground.
  3. Place the ignition switch in the RUN position.

Is the measured voltage within the specified value?

9-14 V

Go to Step 16

Go to Step 12

6

Connect a DMM between the LH electric actuator harness connector terminal 10 (circuit 541) and terminal 7 (circuit 150).

Is the measured voltage within the specified value?

9-14 V

Go to Step 8

Go to Step 9

7

Repair a poor connection or an open in circuit 541 (BRN) between the fuse block terminal B 2 and the LH electric actuator harness connector terminal 10.

Is the repair complete?

--

Go To Step 18

--

8

  1. Connect a DMM between the LH electric actuator harness connector terminal 8 (circuit 733) and ground.
  2. Place the ignition switch in the RUN position.
  3. Move the temperature control knob from WARM to COOL and COOL to WARM.

Does the measured voltage vary within the specified value?

1-12 V

Go to Step 10

Go to Step 11

9

Locate and Repair a poor connection or an open in circuit 150 (BLK) between the LH electric actuator harness connector terminal 7 and G 200.

Is the repair complete?

--

Go To Step 18

--

10

  1. Check for a poor connection at the LH electric actuator. Repair or replace, if necessary.
  2. Check for a binding air temperature valve. Repair or replace, if necessary.
  3. Replace the LH electric actuator. Refer to Temperature Actuator Replacement (LH) .

Is the repair complete?

--

Go To Step 18

--

11

Locate and repair a poor connection or an open in circuit 733 (LT BLU) between The heater-A/C control harness connector C 2 terminal  G and the LH electric actuator harness connector terminal 8.

Is the repair complete?

--

Go To Step 18

--

12

Repair a poor connection or an open in circuit 541 (BRN) between the heater-A/C control harness connector C 2 terminal C and the fuse block terminal B 2.

Is the repair complete?

--

Go To Step 18

--

13

  1. Place the ignition switch in the OFF position.
  2. Disconnect the heater-A/C control connector.
  3. Connect a DMM from the heater-A/C control harness connector C 2, terminal G (circuit 733) to ground.
  4. Check for a short to ground in circuit 733 (LT BLU).

Is the circuit shorted to ground?

--

Go to Step 14

Go to Step 15

14

Locate and repair a short to ground in circuit 733 (LT BLU).

Is the repair complete?

--

Go To Step 18

--

15

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

Is the repair complete?

--

Go To Step 18

--

16

Connect a DMM between the heater-A/C control harness connector C 2 terminal  C (circuit 541) and terminal K (circuit 150).

Is the measured voltage within the specified values?

9 14V

Go To Step 13

Go To Step 17

17

Locate and repair a poor connection or an open in circuit 150 (BLK) between the heater-A/C control harness connector C 2, terminal K and ground G 200.

Is the repair complete?

--

Go To Step 18

--

18

Verify that the system operates properly. Does the system operate properly?

--

System OK

Go to Symptoms