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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Regal (China) (CNG) 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Temperature Control Inoperative

Temperature Control Inoperative C60

Important: To avoid misdiagnosis, be sure to zero the DMM before taking measurements.

Step

Action

Value(s)

Yes

No

1

Check the fuse B3-B4 in the fuse block.

Is the fuse open?

--

Go to Step 2

Go to Step 3

2

Repair a short to ground in circuit 41.

Has the repair been made?

--

Go to Functional Check

--

3
  1. Turn the ignition switch to the RUN position.
  2. Using a Digital Multimeter (DMM) backprobe between the HVAC control assembly harness connector C2 terminal G 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 front LH temperature actuator connector.
  2. Connect a DMM, between the front LH temperature actuator harness connector terminal 10 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 HVAC control assembly harness connector C2.
  2. Connect a DMM, between the HVAC control assembly connector C2 terminal C and ground.
  3. Turn the ignition switch to the RUN position.

Is the measured voltage within the specified value?

9-14 V

Go to Step 13

Go to Step 12

6

Connect a DMM, between the front LH temperature actuator harness connector between terminal 10 and terminal 7 .

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 41 between S233 and the front LH temperature actuator harness connector terminal 10.

Has the repair been made ?

--

Go to Functional Check

--

8
  1. Connect a DMM, between the front LH temperature actuator harness connector terminal 8 and ground.
  2. Turn the ignition switch to 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

Repair a poor connection or an open in circuit 1450 between the front LH temperature actuator harness connector terminal 7 and G200.

Has the repair been made?

--

Go to Functional Check

--

10
  1. Check for a poor connection at the front LH temperature actuator.
  2. Check for a binding air temperature valve.
  3. Replace the front LH temperature actuator. Refer to Temperature Actuator Replacement .

Has the repair been made?

--

Go to Functional Check

--

11

Repair a poor connection or an open in circuit 1199

Has the repair been made?

--

Go to Functional Check

--

12

Repair a poor connection or an open in circuit 41 between S 233 and the HVAC control assembly harness connector C2 terminal C.

Has the repair been made and the system rechecked?

--

Go to Functional Check

--

13
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the front LH temperature actuator connector.
  3. Using a DMM, check for a short to ground in circuit 1199.

Is the circuit shorted to ground?

--

Go to Step 14

Go to Step 15

14

Repair a short to ground in circuit 1199.

Has the repair been made?

--

Go to Functional Check

--

15

Replace the front HVAC control assembly. Refer to Control Assembly Replacement .

Has the repair been made and the system rechecked?

--

Go to Functional Check

--