GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 AURA 🢒 HVAC 🢒 HVAC - Automatic 🢒 HVAC Compressor Clutch Does Not Engage

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The A/C compressor relay output is disabled if engine coolant temperature is above 128°C (262°F). The instrument panel engine coolant indicator will indicate overheating.

  1. Place the mode switch in any position except OFF, and place the air temperature control switch in a cold setting. Use the bi-level mode for consistent testing of the A/C system operation.

    2.

  2. The HVAC control module is inoperative if the module does not respond to any operator control requests.

Step

Action

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The A/C compressor clutch will not engage if an A/C request has been made, and a Powertrain DTC has not been set.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Start the engine.
  2. Observe the instrument panel (I/P) coolant temperature indicator and the driver information center.

Is the engine coolant temperature indicator indicating an over heat status or is the driver information center indicating low coolant?

Go to Engine Overheating

Go to Step 3

3

Important: For A/C compressor operation, the ambient air temperature must be above 4°C (40°F).

  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Place the A/C request switch in the ON position.
  4. Place the air temperature switch in the coldest position.

Does the A/C compressor clutch engage?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4
  1. Open the window in order to ventilate the interior of the vehicle.
  2. If the A/C system was operating, then wait for approximately 2 minutes.
  3. Turn OFF the ignition.
  4. Install the J 43600 ACR 2000 Air Conditioning Service Center.
  5. Record the ambient air temperature at the vehicle.
  6. Record readings of the low and high side STATIC pressures.
  7. Compare the low side pressure values and the high side pressure values with the allowable limits for the recorded ambient air temperature. Refer to Air Conditioning (A/C) System Performance Test .

Are the pressure values within the allowable limits for the recorded ambient air temperature, and within 103 kPa (15 psi) of each other?

Go to Step 5

Go to Leak Testing

5
  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the A/C High Side Pressure Sensor parameter in the powertrain control module data list.
  3. Compare the scan tool A/C High Side Pressure parameter to the high side pressure values on the J 43600 .

Are the high side pressure values within 103 kPa (15 psi) of each other?

Go to Step 6

Go to Step 23

6

Is the HVAC control module inoperative?

Go to Step 16

Go to Step 7

7
  1. Start the engine.
  2. With a scan tool, observe the A/C Request Signal parameter in the poertrain control module (PCM) data list.
  3. Place the air temperature switch in the coldest position.
  4. Place the A/C request switch in the ON position.

Does the scan tool indicate that the A/C Request Signal parameter is YES?

Go to Step 10

Go to Step 8

8
  1. Start the engine.
  2. With a scan tool, observe the A/C Switch parameter in the body control module (BCM) data list.
  3. Place the air temperature switch in the coldest position.
  4. Place the A/C request switch in the ON position.

Does the scan tool indicate that the A/C Switch parameter is ON?

Go to Step 9

Go to Step 18

9
  1. Turn OFF the ignition.
  2. Test the A/C request signal circuit for the following:
    3. • A short to voltage
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 10

10

With a scan tool, command the A/C compressor clutch relay ON and OFF.

Does the clutch relay turn ON and OFF with each command?

Go to Step 14

Go to Step 11

11
  1. Turn OFF the ignition.
  2. Disconnect the A/C compressor clutch relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side of the voltage supply circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 12

Go to Step 26

12
  1. Connect a test lamp between the control circuit and the coil side of the voltage supply circuit.
  2. With a scan tool, command the A/C compressor clutch relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 28

Go to Step 13

13

Does the test lamp remain illuminated with each command?

Go to Step 21

Go to Step 20

14
  1. Turn OFF the ignition.
  2. Disconnect the A/C compressor clutch relay.
  3. Probe the switch side of the voltage supply circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 15

Go to Step 25

15
  1. Connect a 10-amp fused jumper between the switch side voltage circuit of the clutch relay and the supply voltage circuit of the clutch.
  2. Turn ON the ignition, with the engine OFF.

Does the A/C compressor clutch engage?

Go to Step 28

Go to Step 22

16

Test the ignition 3 voltage circuit of the HVAC control module for the following:

    • A short to ground
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 17

17

Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 30

18
  1. Start the engine.
  2. Place the A/C request in the ON position.
  3. Measure the voltage on the request circuit at the BCM to a good ground.

Does the value measure near battery voltage?

Go to Step 31

Go to Step 19

19

Test the A/C request signal circuit for a high resistance, open or a short to ground. Refer to Circuit Testing and to Wiring Repairs .

Did you complete the repair?

Go to Step 39

Go to Step 30

20

Test the control circuit of the A/C compressor clutch relay for an open. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 32

21

Test the control circuit of the A/C compressor clutch relay for a short to ground. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 32

22

Test the supply voltage circuit at the A/C compressor clutch for the following:

    • A short to ground
    • A high resistance
    • An open

Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 24

23

Test the ground circuit of the A/C refrigerant pressure sensor for an open. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 27

24

Test the ground circuit of the A/C compressor clutch for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 29

25

Repair the switch side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 39

--

26

Repair the coil side of the voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 39

--

27

Inspect for poor connections at the harness connector of the A/C high pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 33

28

Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 34

29

Inspect for poor connections at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .

Did you find and correct the condition?

Go to Step 39

Go to Step 35

30

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 .

Did you find and correct the condition?

Go to Step 39

Go to Step 36

31

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

Did you find and correct the condition?

Go to Step 39

Go to Step 37

32

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

Did you find and correct the condition?

Go to Step 39

Go to Step 38

33

Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement .

Did you complete the replacement?

Go to Step 39

--

34

Replace the A/C compressor clutch relay.

Did you complete the replacement?

Go to Step 39

--

35

Replace the A/C compressor clutch assembly. Refer to Compressor Clutch Assembly Replacement .

Did you complete the replacement?

Go to Step 39

36

Replace the HVAC control module. Refer to Control Module References for HVAC replacement, setup, and programming.

Did you complete the replacement?

Go to Step 39

--

37

Replace the BCM. Refer to Control Module References for BCM replacement, setup, and programming.

Did you complete the replacement?

Go to Step 39

--

38

Replace the PCM. Refer to Control Module References for PCM replacement, setup, and programming.

Did you complete the replacement?

Go to Step 39

--

39

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 4