GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to Diagnostic System Check

2

Inspect the HVAC fuse in the fuse block.

Is the HVAC fuse open?

--

Go to Step 3

Go to Step 4

3

Repair short to ground in circuit 41 (BRN). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 13

--

4

  1. Turn the ignition switch off.
  2. Disconnect the left electric actuator electrical connector.
  3. Turn the ignition switch on.
  4. Use a digital multimeter (DMM) to measure the voltage between the left electric actuator harness connector terminal 5 and ground.
  5. Is the measured voltage within the specified range?

9-14V

Go to Step 6

Go to Step 5

5

Repair the poor connection or open in circuit 41 (BRN). Refer to Testing for Intermittent Conditions and Poor Connections and Circuit Testing in Wiring Systems.

Is the repair complete?

--

Go to Step 13

--

6

  1. Use a DMM in order to measure the voltage between the left electric actuator harness connector terminal 6 and ground.
  2. Vary the driver temperature knob from full cold to full hot.

Does the voltage vary within the specified range?

0.5-4.5V

Go to Step 7

Go to Step 8

7

Replace the left electric actuator. Refer to Temperature Actuator Replacement (LH) .

Is the repair complete?

--

Go to Step 13

--

8

Inspect for a short to ground or short to B+ in circuit 1199 (DK BLU). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is there a short to ground or short to B+ in circuit 1199 (DK BLU)?

--

Go to Step 9

Go to Step 10

9

Locate and repair the short to ground or the short to B+ in circuit 1199 (DK BLU).

Is the repair complete?

--

Go to Step 13

--

10

Inspect for a poor connection or open in circuit 1199 (DK BLU) between the heater-A/C control harness connector terminal C7 and the left electric actuator harness connector terminal 6.

Is there continuity in circuit 1199 (DK BLU)?

--

Go to Step 11

Go to Step 12

11

Repair the poor connection or open in circuit 1199 (DK BLU) between the heater-A/C control harness connector terminal C7 and the left electric actuator harness connector terminal 6. Refer to Testing for Intermittent Conditions and Poor Connections and Circuit Testing in Wiring Systems.

Is the repair complete?

--

Go to Step 13

--

12

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

Is the repair complete?

--

Go to Step 13

--

13

Verify that the system operates properly.

Does the system operate properly?

--

System OK

Go to Diagnostic System Check