GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Monte Carlo 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Passenger Temperature Control Inoperative

Step

Action

Value(s)

Yes

No

Important: Perform the following steps In order to avoid misdiagnosis:

    • Inspect and ensure that the coolant ratio is correct and the heater hose lines are not frozen.
    • Zero the digital multimeter (DMM) before taking measurements.

1

Did you perform the HVAC Air Delivery System Check?

--

Go to Step 2

Go to HVAC Compressor Controls System Check

2

Inspect the fuse block for an open in fuse 4.

Is there an open in fuse 4?

--

Go to Step 3

Go to Step 4

3

Repair a short to ground in CKT 41 (BRN) .

Is the repair complete?

--

System OK

--

4
  1. Disconnect the heater-A/C control connector C2.
  2. Place the ignition switch in the RUN position.
  3. Use a digital multimeter (DMM) in order to probe between the heater-A/C control harness connector C2 between terminal B7 and terminal B8.

Is the measured voltage within the specified range?

9-14 V

Go to Step 8

Go to Step 5

5

Use a DMM in order to probe between the heater-A/C control harness connector C2 terminal B7 and ground.

Is the measured voltage within the specified range?

9-14 V

Go to Step 7

Go to Step 6

6

Locate and repair a poor connection or open in CKT 41 (BRN) between the fuse block terminal D10 and the heater-A/C control harness connector C2 terminal B7.

Is the repair complete?

--

System OK

--

7

Locate and repair a poor connection or open in CKT 150 (BLK) between the heater-A/C control harness connector C2 terminal B8 and G205.

Is the repair complete?

--

System OK

--

8
  1. Place the ignition switch in the OFF position.
  2. Reconnect the heater-A/C control connector C2.
  3. Disconnect the right electric actuator.
  4. Place the ignition switch in the RUN position.
  5. Use a DMM in order to probe between the right electric actuator harness connector terminal 10 and terminal 7.

Is the measured voltage within the specified range?

9-14 V

Go to Step 12

Go to Step 9

9

Use a DMM in order to probe between the right electric actuator harness connector terminal 10 and ground.

Is the measured voltage within the specified range?

9-14 V

Go to Step 11

Go to Step 10

10

Locate and repair a poor connection or an open in CKT 41 (BRN) between S233 and the right electric actuator harness connector terminal 10.

Is the repair complete?

--

System OK

--

11

Locate and repair a poor connection or an open in CKT 150 (BLK) between the right electric actuator harness connector terminal 7 and G205.

Is the repair complete?

--

System OK

--

12
  1. Use a DMM in order to probe between the right electric actuator harness connector terminal 8 and ground.
  2. Move the temperature control from HOT to COLD and COLD to HOT positions.

Is the measured voltage within the specified range?

1-12 V

Go to Step 13

Go to Step 14

13
  1. Replace the right electric actuator Refer to Temperature Actuator Replacement .
  2. Inspect the system.

Is the repair complete?

--

System OK

--

14

Inspect for a short to ground or a short to B+ in CKT 1236 (WHT/BLK) .

Does a short to ground or a short to B+ exist in CKT 1236 (WHT/BLK)?

--

Go to Step 15

Go to Step 16

15

Repair the short to ground or short to B+ in CKT 1236 (WHT/BLK).

Is the repair complete?

--

System OK

--

16

Inspect for a poor connection or an open in CKT 1236 (WHT/BLK).

Does a poor connection or open exist in CKT 1236 (WHT/BLK)?

--

Go to Step 17

Go to Step 18

17

Repair the poor connection or open in CKT 1236 (WHT/BLK).

Is the repair complete?

--

System OK

--

18

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

Is the repair complete?

--

System OK

--