GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Savana 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Temperature Actuator Inoperative

Step

Action

Value(s)

Yes

No

1

Was the HVAC Air Delivery System Check performed?

--

Go to Step 2

Go to HVAC Air Delivery System Check

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

Go to Step 14

3
  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 6

Go to Step 4

4
  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 5

Go to Step 16

5
  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 end black vacuum tube at the water valve for air flow.

Is air flow present at the water valve?

--

Go to Step 17

Go to Step 18

6
  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 an unpowered test lamp between the temperature valve actuator motor connector, cavity 10 for CKT 141 (BRN), and ground.

Does the test lamp light?

--

Go to Step 7

Go to Step 19

7

Connect an ohmmeter between the valve actuator motor connector, cavity 7 for CKT 150 (BLK), and ground.

Does the circuit have continuity?

--

Go to Step 8

Go to Step 20

8
  1. Connect a voltmeter to the 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.

Is voltage present and does it vary?

--

Go to Step 21

Go to Step 9

9
  1. Disconnect the heater and A/C controller connector C2.
  2. Connect an unpowered test lamp between the heater and A/C controller connector C2, cavity E for CKT 141 (BRN), and ground.

Does the test lamp light?

--

Go to Step 10

Go to Step 23

10
  1. Disconnect the heater and A/C controller connector C1.
  2. Connect an ohmmeter between the heater and A/C controller connector C1, cavity B for CKT 150 (BLK), and ground.

Does the circuit have continuity?

--

Go to Step 11

Go to Step 24

11

Connect an unpowered test lamp between the heater and A/C controller connector C2, cavity F for CKT 733 (LT BLU), and ground.

Does the test lamp light?

--

Go to Step 25

Go to Step 12

12

Connect an ohmmeter between the heater and A/C controller connector C2, cavity F for CKT 733, and ground.

Does the circuit have continuity?

--

Go to Step 26

Go to Step 13

13

Connect an ohmmeter between the heater and A/C controller connector C2, cavity F, and the temperature valve actuator motor connector, cavity 8, in CKT 733 (LT BLU).

Does the circuit have continuity?

--

Go to Step 27

Go to Step 28

14

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

Is the engine coolant flow path open?

--

Go to Step 15

Go to Heating Insufficient

15

Replace the water valve.

Refer to Heater Water Bypass Valve Replacement

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

16
  1. Inspect the vacuum supply from the engine to the heater for the following conditions:
    2. • A loose tubing connection
    • A tube leak
    • A crimped tube
  2. Repair any condition, as needed.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

17

Replace the heater and A/C controller.

Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

18
  1. Inspect the white/black vacuum tube from the heater and A/C controller to the water valve for the following conditions:
    2. • A loose tubing connection
    • A tube leak
    • A crimped tube
  2. Repair any condition, as needed.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

19

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

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

20

Repair the open in CKT 150 (BLK) between the temperature valve actuator motor and ground G201.

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

21
  1. Inspect the temperature valve door for any mechanical condition.
  2. Repair the mechanical condition.

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

--

Go to HVAC Air Delivery System Check

Go to Step 22

22

Replace the temperature valve actuator motor.

Refer to Mode Actuator Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

23

Repair the open in CKT 141 (BRN) between splice S215 and the heater and A/C controller.

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

24

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

Refer to Wiring Repairs .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

25

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 .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

26

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 .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

27

Replace the heater and A/C controller.

Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

28

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 .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--