GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Savana 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Temperature Actuator Inoperative

Step

Action

Value(s)

Yes

No

1

Did you review the HVAC blower operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms

2
  1. Start the engine.
  2. Allow the engine to reach operating temperature.
  3. Place the mode switch on the heater and A/C controller in the heat position.
  4. Place the blower motor switch in the HI position.
  5. Observe the air output from the blower motor.
  6. Place the mode switch on the heater and A/C controller in the A/C position.
  7. Observe the air output from the blower motor.

Does the blower motor produce heated, then cooled air?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3
  1. Place the ignition switch in the OFF position.
  2. Ensure all fuses are in good condition.
  3. Ensure all grounds are clean and tight.
  4. Disconnect the black vacuum tube at the water valve.
  5. Connect a vacuum pump to the water valve.
  6. Start the engine.
  7. Allow the engine to reach operating temperature.
  8. Place the mode switch on the heater and A/C controller in the heat position.
  9. Place the blower motor switch in the HI position.
  10. Apply the specified vacuum to the water valve.
  11. Observe any heat output from the blower motor.

Does the blower motor produce heated air?

60 kPa (8.7 lb/sq in)

Go to Step 4

Go to Step 15

4
  1. Adjust the temperature control knob on the heater and A/C controller to the hot, or red, end of travel.
  2. Place a vacuum gauge on the black vacuum tube to the water valve.

Does the vacuum gauge indicate a vacuum greater than the specified value?

60 kPa (8.7 lb/sq in)

Go to Step 7

Go to Step 5

5
  1. Disconnect the vacuum connector at the heater and A/C controller.
  2. Connect a vacuum gauge at the heater and A/C controller's black vacuum tube, the vacuum supply, for the side connector's pin 1.

Does the vacuum gauge indicate a vacuum greater than the specified value?

60 kPa (8.7 lb/sq in)

Go to Step 6

Go to Step 17

6
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the white vacuum tube from the heater and A/C controller, pin 2.
  3. Blow air through the white vacuum tube from the heater and A/C controller while observing the black vacuum tube at the water valve for air flow.

Is air flow present at the water valve?

--

Go to Step 28

Go to Step 19

7
  1. Turn the ignition switch to the OFF position.
  2. Reconnect all vacuum tubing.
  3. Disconnect the electrical connector at the temperature valve actuator motor.
  4. Place the ignition switch in the RUN position.
  5. Connect a J 35616-200 unpowered test lamp between temperature valve actuator motor connector cavity 10 for CKT 141 (BRN) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp light?

--

Go to Step 8

Go to Step 20

8

Connect a J 39200 digital multimeter (DMM) between valve actuator motor connector cavity 7 for CKT 150 (BLK) and ground. Refer to Circuit Testing in Wiring Systems.

Does the circuit have continuity?

--

Go to Step 9

Go to Step 21

9
  1. Connect a J 39200 DMM between temperature valve actuator motor connector cavity 8 for CKT 733 (LT BLU) and ground.
  2. While you monitor voltage, adjust the position of the temperature control knob. Refer to Circuit Testing in Wiring Systems.

Is voltage present and does it vary?

--

Go to Step 22

Go to Step 10

10
  1. Disconnect heater and A/C controller connector C2.
  2. Connect a J 35616-200 unpowered test lamp between heater and A/C controller connector C2 cavity E for CKT 141 (BRN) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp light?

--

Go to Step 11

Go to Step 24

11
  1. Disconnect heater and A/C controller connector C1.
  2. Connect a J 39200 DMM between heater and A/C controller connector C1, cavity B for CKT 150 (BLK), and ground. Refer to Circuit Testing in Wiring Systems.

Does the circuit have continuity?

--

Go to Step 12

Go to Step 25

12

Connect a J 35616-200 unpowered test lamp between heater and A/C controller connector C2 cavity F for CKT 733 (LT BLU) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp light?

--

Go to Step 26

Go to Step 13

13

Connect a J 39200 DMM between heater and A/C controller connector C2 cavity F for CKT 733 and ground. Refer to Circuit Testing in Wiring Systems.

Does the circuit have continuity?

--

Go to Step 27

Go to Step 14

14

Connect a J 39200 DMM between heater and A/C controller connector C2 cavity F and temperature valve actuator motor connector cavity 8 for CKT 733 (LT BLU). Refer to Circuit Testing in Wiring Systems.

Does the circuit have continuity?

--

Go to Step 28

Go to Step 29

15

Inspect the engine coolant flow through the heater core for any restriction.

Is the engine coolant flow path open?

--

Go to Step 16

Go to Heating Insufficient

16

Replace the water valve.

Refer to Heater Water Valve Replacement .

Is the repair complete?

--

Go to Step 30

--

17

Inspect the vacuum supply from the engine to the heater for the following conditions:

  1. A loose tubing connection
  2. A tube leak
  3. A crimped tube

Did you find and correct a condition with the engine vacuum supply?

--

Go to Step 30

Go to Step 18

18

Check the engine for a mechanical condition which might cause low vacuum.

Refer to the appropriate section:

    •  Symptoms in Engine Controls - 4.3L
    •  Symptoms in Engine Controls - 5.0,5.7L
    •  Symptoms in Engine Controls - 6.5L
    •  Symptoms in Engine Controls - 7.4L

Did you find and correct the condition?

--

Go to Step 30

Go to Step 3

19

Inspect the white/black vacuum tube from the heater and A/C controller to the water valve for the following conditions:

  1. A loose tubing connection
  2. A tube leak
  3. A crimped tube
  4. A blocked vacuum line

Did you find and correct a vacuum condition?

--

Go to Step 30

--

20

Repair the open in CKT 141 (BRN) between the instrument panel fuse block and the temperature valve actuator motor connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

21

Repair the open in CKT 150 (BLK) between the temperature valve actuator motor and ground G201. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

22

Inspect the temperature valve door for any mechanical condition.

Did you find and repair a mechanical condition with the temperature valve door?

--

Go to Step 30

Go to Step 23

23

Replace the temperature valve actuator motor. Refer to Temperature Actuator Replacement .

Is the repair complete?

--

Go to Step 30

--

24

Repair the open in CKT 141 (BRN) between splice S215 and the heater and A/C controller. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

25

Repair the open in CKT 150 (BLK) between the heater and A/C controller connector and splice S202. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

26

Repair the short to voltage in CKT 733 (LT BLU) between the temperature valve actuator motor connector and the heater and A/C controller connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

27

Repair the short to ground in CKT 733 (LT BLU) between the temperature valve actuator motor connector and the heater and A/C controller connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

--

28

Replace the heater and A/C controller. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to Step 30

--

29

Repair the open in CKT 733 (LT BLU) between the heater and A/C controller connector and the temperature valve actuator motor connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 30

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30

Operate the heater and the A/C in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3