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Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC Suburban - 4WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Mode Actuator Inoperative

Mode Actuator Inoperative Front

Step

Action

Value(s)

Yes

No

1

Has the HVAC Air Delivery System Check been performed?

--

Go to Step 2

Go to HVAC Air Delivery System Check

2
  1. Place the ignition switch in the RUN position.
  2. Disconnect the connector at the front mode door motor.
  3. Connect a J 39200  (volts) between the front mode door motor connector, cavity 10, and ground.

Is battery voltage present?

--

Go to Step 4

Go to Step 3

3

Locate and repair the open in CKT 141 (BRN) between the IP fuse block and the front mode door motor. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

4

Connect a J 39200  (continuity) between the front mode door motor connector, cavity 7, and ground.

Is continuity present?

--

Go to Step 6

Go to Step 5

5

Locate and repair the open in CKT 150 (BLK) between the front mode door motor and splice S244. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

6
  1. Place the ignition switch in the RUN position.
  2. Place the blower switch on the HVAC control module in the LO position.
  3. Make sure that the front blower motor is operating.
  4. Connect a J 39200  (volts) from the front mode door motor connector, cavity 8, to ground.
  5. Adjust the position of the mode control dial while observing the J 39200 response.

Is the J 39200 response a smooth, variable voltage?

--

Go to Step 9

Go to Step 7

7
  1. Disconnect connector C3 at the HVAC control module.
  2. Connect a J 39200  (volts) between pin 9 of the HVAC control module, and ground.
  3. Adjust the position of the mode control dial while observing the J 39200 response.

Is the J 39200 response a smooth, variable voltage?

--

Go to Step 8

Go to Step 10

8

Locate and repair the open or cause of resistance in CKT 454 (WHT) between the HVAC control module and the front mode door motor. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

9

Replace the front mode door motor. Refer to Mode Actuator Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

10

Replace the HVAC control module. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

Mode Actuator Inoperative Rear

Step

Action

Value(s)

Yes

No

1

Has the HVAC Air Delivery System Check been performed?

--

Go to Step 2

Go to HVAC Air Delivery System Check

2
  1. Place the ignition switch in the RUN position.
  2. Backprobe a J 39200  (volts) from the auxiliary HVAC control logic module connector, cavity F, to ground.
  3. Adjust the mode control dial at the front and rear auxiliary HVAC control modules while monitoring the J 39200 .

Does the J 39200 indicate a smooth, variable voltage?

--

Go to Step 3

Go to Step 10

3
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the connector at the auxiliary HVAC control logic module.
  3. Disconnect the auxiliary mode door motor connector.
  4. Connect a J 39200  (continuity) between the auxiliary HVAC control logic module connector, cavity F, and cavity 8 of the auxiliary mode door motor connector.

Is continuity present?

--

Go to Step 5

Go to Step 4

4

Locate and repair the open in CKT 454 (WHT) between the auxiliary HVAC control logic module and the auxiliary mode door motor. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

5

Connect a J 39200  (continuity) between cavity 7 of the auxiliary mode door motor connector and ground.

Is continuity present?

--

Go to Step 7

Go to Step 6

6

Locate and repair the open in CKT 150 (BLK) between the auxiliary mode door motor and splice S403. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

7

Connect a J 39200  (volts) between cavity 10 of the auxiliary mode door motor connector and ground.

Is battery voltage present?

--

Go to Step 9

Go to Step 8

8

Locate and repair the open in CKT 341 (BRN) between the auxiliary mode door motor and splice S400. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

9

Replace the auxiliary mode door motor. Refer to Auxiliary Mode Valve Actuator Replacement .

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

10
  1. Disconnect the auxiliary HVAC control logic module.
  2. Connect a J 39200 (volts) between cavity J of the auxiliary HVAC control logic module connector and ground.

Is voltage present?

--

Go to Step 12

Go to Step 11

11

Locate and repair the open in CKT 341 (BRN) between the auxiliary HVAC control logic module and splice S308. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

12
  1. Connect a J 39200 (volts) between cavity E of the auxiliary HVAC control logic module connector and ground.
  2. Repeat the same test for cavity D.

Does the J 39200 indicate a smooth, variable voltage?

--

Go to Step 13

Go to Step 14

13

Replace the auxiliary HVAC control logic module.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

14
    • If cavity E of step 12 failed complete the following test for the front auxiliary HVAC control module.
    • If cavity D of step 12 failed complete the following test for the rear auxiliary HVAC control module.
    • If both circuits failed complete the following test for both control modules.
        1. Backprobe a J 39200 (volts) between cavity J of the auxiliary HVAC control module being tested and ground.
        2. Adjust the mode control dial at the auxiliary HVAC control module while monitoring the J 39200 .

Does the J 39200 indicate a smooth, variable voltage?

--

Go to Step 16

Go to Step 15

15

Replace the auxiliary HVAC module that was tested in step 14. Refer to Auxiliary Air Conditioning (A/C) Control Assembly Replacement - Front (front) or Control Assembly Replacement - Auxiliary (rear).

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--

16

Locate the open or cause of resistance in CKT 920 (DK BLU) between the auxiliary HVAC control logic module and the rear auxiliary HVAC control module and the or CKT 919 (LT BLU) to the front auxiliary HVAC control module. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to HVAC Air Delivery System Check

--