GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the heater-A/C control diagnosis system check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

Check 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.

Is the repair complete?

--

System OK

--

4

  1. Turn the ignition switch off.
  2. Disconnect the RH electric actuator electrical connector.
  3. Turn the ignition switch on.
  4. Using a DMM, measure the voltage between the RH electric actuator harness connector terminal 5 and ground.

Is the measured voltage within the specified value?

9-14V

Go to Step 6

Go to Step 5

5

Repair poor connection or open in circuit 41.

Is the repair complete?

--

System OK

--

6

  1. Using a DMM, measure the voltage between the RH electric actuator harness connector terminal 6 and ground.
  2. Vary the passenger temperature knob from full cold to full hot.
  3. Check if voltage varies between 0.5V and 4.5V.

Does the voltage vary?

--

Go to Step 7

Go to Step 8

7

Replace the RH electric actuator. Refer to Temperature Actuator Replacement .

Is the repair complete?

--

System OK

--

8

Check for short to ground or short to B+ in circuit 1236.

Is there a short to ground or short to B+ in circuit 1236?

--

Go to Step 9

Go to Step 10

9

Repair short to ground or short to B+ in circuit 1236.

Is the repair complete?

--

System OK

--

10

Check for a poor connection or open in circuit 1236 between the heater-A/C control harness connector terminal C6 and the RH electric actuator harness connector terminal 6.

Is there continuity in circuit 1236?

--

Go to Step 11

Go to Step 12

11

Repair poor connection or open in circuit 1236 between the heater-A/C control harness connector terminal C6 and the RH electric actuator harness connector terminal 6.

Is the repair complete?

--

System OK

--

12

Replace the heater-A/C control. For manual systems refer to Control Assembly Replacement and for automatic systems refer to Control Assembly Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

System OK

--