GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform a System Diagnostic check ?

--

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

Locate and 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 19

--

4

  1. Turn the ignition switch to the ON position.
  2. Use a Digital Multi Meter (DMM) to backprobe the heater-A/C control harness connector C2 from terminal B5 to ground.
  3. Move the temperature control knob from HOT to COLD, and COLD to HOT.

Does the measured voltage vary within the specified value?

1-12 V

Go to Step 5

Go to Step 6

5

  1. Disconnect the RH electric actuator connector.
  2. Connect a DMM between the RH electric actuator harness connector terminal 10 and ground.

Is the measured voltage within the specified value?

B+

Go to Step 7

Go to Step 8

6

  1. Disconnect the heater-A/C control harness connector  C2.
  2. Connect a DMM between the heater-A/C control harness connector C2 terminal B7 and ground.

Is the measured voltage within the specified value?

B+

Go to Step 17

Go to Step 13

7

Connect a DMM between the RH electric actuator harness connector terminal 10 and terminal 7.

Is the measured voltage within the specified value?

B+

Go to Step 9

Go to Step 10

8

Locate and repair a poor connection or an open in circuit 41 (BRN) between S233 and the RH electric actuator harness connector terminal 10.Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

9

  1. Connect a DMM between the RH electric actuator harness connector terminal 8 and ground.
  2. Keep the heater-A/C control connector connected.
  3. Move the temperature control knob from HOT to COLD and COLD to HOT.

Does the measured voltage vary within the specified value?

1-12V

Go to Step 11

Go to Step 12

10

Locate and repair a poor connection or an open in circuit  150 (BLK) between the RH electric actuator harness connector terminal 7 and S213. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

11

  1. Inspect for poor connection at the RH electric actuator.
  2. Test for a binding air temperature valve.
  3. If OK, then replace the RH electric actuator. Refer to Temperature Actuator Replacement .

Is the repair complete?

--

Go to Step 19

--

12

Locate and repair a poor connection or an open in circuit 1199 (DK BLU) between the heater-A/C control harness connector C2 terminal B5 and the RH electric actuator harness connector terminal 8. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

13

Locate and repair a poor connection or an open in circuit 41 (BRN) between the heater-A/C control harness connector C2 terminal B7 and the fuse block terminal B4. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

14

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the heater-A/C control connector.
  3. Use a DMM to measure the resistance between the heater-A/C control harness connector C2 terminal B5 and ground.

Is the measured resistance within the specified range?

Go to Step 16

Go to Step 15

15

Locate and repair a short to ground in circuit 1199 (DK BLU). Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

16

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

Is the repair complete?

--

Go to Step 19

--

17

Connect a DMM between the heater-A/C control harness connector C2 terminals B7 and B8.

Is the measured voltage within the specified range?

B+

Go to Step 14

Go to Step 18

18

Locate and repair a poor connection or an open in circuit 150 (BLK) between the heater-A/C control harness connector C2 terminal B8 and G205. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 19

--

19

Verfiy that the system operates properly .

Does the system operate properly ?

--

System OK

Go to Symptoms