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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 Rendezvous - FWD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Too Hot in Vehicle

Diagnostic Aids

The Mitsubishi scroll type A/C compressor carries an internal thermal cut off switch. The thermal cut off switch normal operation is to open and disable the compressor under extreme load and temperatures above 155°C (311°F). The internal thermal cut off switch is non-serviceable.

Test Description

The number below refers to the step number on the diagnostic table.

  1. The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.

1

Important: Both the left and the right air temperature controls are diagnosed in this table.

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the blower motor switch in each speed position.

Does the blower motor operate in any of the speed positions?

--

Go to Step 3

Go to Blower Motor Inoperative

3

Does the blower motor operate in each speed position?

--

Go to Step 4

Go to Blower Motor Malfunction

4

Does the Too Hot in Vehicle concern occur when A/C cooling is desired?

--

Go to Step 5

Go to Step 7

5

IMPORTANT:: For A/C compressor operation, the ambient air temperature must be above 3°C (38°F).

  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the mode switch in the VENT position.
  4. Place the A/C request switch in the ON position.
  5. Place both temperature switches in the coldest position.

Does the A/C compressor operate?

--

Go to Step 6

Go to HVAC Compressor Clutch Does Not Engage

6

Perform the refrigerant system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 7

7
  1. Observe the drive shaft of the air temperature actuator.
  2. Place the air temperature switch from the coldest to the warmest position.

Does the drive shaft of the air temperature actuator rotate?

--

Go to Step 8

Go to Step 9

8

Inspect the air temperature door and the air temperature actuator for the following conditions:

    • A misaligned air temperature actuator
        Refer to Air Temperature Actuator Replacement .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within the full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

--

Go to Step 18

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

9

Test the ignition 3 voltage circuit of the air temperature actuator for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 10

10

Test the ground circuit of the air temperature actuator for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 11

11

Test the control circuit of the air temperature actuator for an open, for a high resistance, for a short to ground, or for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 12

12

Important: Ensure that the HVAC control module connector is connected during this step in order to avoid misdiagnosis.

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage from the door control circuit of the air temperature actuator to a good ground.
  3. Place the air temperature switch from the coldest position to the warmest position.

Is the voltage within the specified values with a smooth transition between cold and hot?

0 V at cold

12 V at hot

Go to Step 13

Go to Step 15

13

Inspect for poor connections at the harness connector of the air temperature actuator. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 14

14

Inspect the air temperature door and the air temperature actuator for the following conditions:

    • A misaligned air temperature actuator
         Refer to Air Temperature Actuator Replacement .
    • Broken or binding linkages or air temperature door
    • An obstruction that prevents the air temperature door from operating within the full range of motion
    • Missing seals to the air temperature door
    • Misaligned seals to the air temperature door

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

15

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

16

Replace the air temperature actuator. Refer to Air Temperature Actuator Replacement - Right Side or to Air Temperature Actuator Replacement - Left Side .

Did you complete the replacement?

--

Go to Step 18

--

17

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

Did you complete the replacement?

--

Go to Step 18

--

18

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2