GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Rendezvous - FWD 🢒 HVAC 🢒 HVAC - Automatic 🢒 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 numbers below refer to the step numbers on the diagnostic table.

  1. This test is to ensure A/C system is operating normally.

    2.

  2. The aspirator tube connects to the rear of the HVAC control module. The aspirator tube is used to draw air past the inside air temperature sensor.

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.

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the DTC List in Vehicle DTC Information.

Does the scan tool display any DTC B0165, B0166, B0408, B0418, or B0233?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

Important: Ambient air temperature must be above 3°C (38°F).

  1. Start the engine.
  2. Turn ON the HVAC controls.
  3. Place the drivers temperature knob in the coldest position.
  4. Place the HVAC control head in the AUTO position.

Does the A/C compressor operate?

--

Go to Step  4

Go to HVAC Compressor Clutch Does Not Engage

4

Place the blower motor switch in each speed position.

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

--

Go to Step 5

Go to Blower Motor Inoperative

5

Does the blower motor operate in the desired speeds?

--

Go to Step 6

Go to Blower Motor Malfunction

6
  1. Place the blower motor switch in the maximum speed position.
  2. Place the mode switch in the panel position.
  3. Place the recirculation switch in the ON and OFF positions.

Does the recirculation door operate properly?

--

Go to Step 7

Go to Air Recirculation Malfunction

7

Perform the A/C system performance test. Refer to Air Conditioning (A/C) System Performance Test.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 8

8
  1. Turn ON the ignition, with engine OFF.
  2. With a scan tool, command the right and left air temperature actuators Hot and Cold.
  3. Observe the Right Temp Door Position and the Left Temp Door Position parameters.

Do the counts change when actuators are commanded?

--

Go to Step 9

Go to Step 13

9
  1. Install a thermometer near the inside air temperature sensor.
  2. With a scan tool, observe the Inside Air Temp data parameters in the Heating and Air Conditioning Data list.

Does the scan tool indicate the sensor temperature are within 3°C (5°F) of the thermometer temperatures?

--

Go to Step 11

Go to Step 10

10

Inspect for a blocked aspirator tube of the HVAC control module.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 17

11
  1. Turn the engine OFF.
  2. Install a scan tool.
  3. Cover the sunload sensor.
  4. Start the engine.
  5. Adjust the driver side temperature to 22°C (72°F).
  6. With a scan tool, observe the Sunload Sensor data parameter in the Heating and Air Condition data list.

Does the scan tool indicate that the Sunload Sensor parameter is greater than the specified value?

230 Counts

Go to Step 12

Go to Step 16

12

  1. Uncover the sunload sensor.
  2. Direct a light source at the sunload sensor.

Does the voltage change?

--

System OK

Go to Step 16

13

Test the suspect actuator door control circuit for a short to voltage, a short to ground, an open, or high resistance. Refer to Circuit Testing and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 14

14

Test the suspect actuator ignition 3 voltage circuit for a short to ground, an open, or high resistance. Refer to Circuit Testing and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 15

15

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

Did you find and correct the condition?

--

Go to Step 21

Go to Step 19

16

Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

17

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

Did you find and correct the condition?

--

Go to Step 21

Go to Step 20

18

Replace the sunload sensor. Refer to Sun Load Sensor Replacement.

Did you complete the replacement?

--

Go to Step 21

--

19

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

Did you complete the replacement?

--

Go to Step 21

--

20

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

Did you complete the replacement?

--

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3