GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Grand Prix 🢒 Engine 🢒 Engine Cooling 🢒 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 124°C (255°F) for the LG8 and 121°C (250°F) for the L36.

  1. The HVAC control module is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.

Step

Action

Value(s)

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

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

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2

  1. Start the engine.
  2. Observe the coolant temperature indicator.

Is the engine coolant temperature indicator illuminated?

--

Go to Engine Coolant Temperature Indicator Always On in Engine Cooling

Go to Step 3

3

Important: 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 A/C request switch in the ON position.
  4. Place the air temperature switch in the coldest position.

Does the A/C compressor operate?

--

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

Go to Step 4

4
  1. Park the vehicle inside or in the shade.
  2. Open the windows in order to ventilate the interior of the vehicle.
  3. If the A/C system was operating, then allow the A/C system to equalize for approximately 2 minutes.
  4. Turn OFF the ignition.
  5. Install the J 43600 ACR 2000.
  6. Record the ambient air temperature at the vehicle.
  7. Record readings of the low and high side STATIC pressures.
  8. Compare the pressure values with the allowable specifications for the ambient air temperature. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

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

--

Go to Step 5

Go to Leak Testing in Heating, Ventilation and Air Conditioning

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 engine data 2 list.
  3. Compare the A/C High Side Pressure on the scan tool to the high side pressure value on the ACR2000

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

--

Go to Step 6

Go to Step 19

6

Do the temperature controls operate properly?

--

Go to Step 7 

Go to Step 18

7
  1. Start the engine.
  2. With a scan tool, observe the A/C Request parameter in the Powertrain Control Module engine data 2 list.
  3. Place the air temperature switch in the coldest position.
  4. Place the blower motor switch in the maximum speed position.
  5. Place the A/C request switch in the ON position.

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

--

Go to Step 12

Go to Step 8

8

Does the A/C request indicator illuminate?

--

Go to Step 10

Go to Step 9

9

Important: The blower motor switch must be in the ON position for this step.

  1. Turn the ignition ON.
  2. Check the OFF blower motor control circuit for short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 30

10
  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM).
  3. Turn ON the ignition, with the engine OFF.
  4. Place the air temperature switch in the coldest position.
  5. Place the blower motor switch in the maximum speed position.
  6. Place the A/C request switch in the ON position.
  7. Measure the voltage from the A/C request signal circuit of the PCM to a good ground.

Does the voltage measure within the specified range?

7.0-12.5 V

Go to Step 31

Go to Step 11

11
  1. Turn OFF the ignition.
  2. Test the A/C request signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 30

12

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

Does the A/C compressor clutch relay turn ON and OFF with each command?

--

Go to Step 16

Go to Step 13

13
  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 voltage supply circuit of the A/C compressor clutch relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 26

14
  1. Connect a test lamp between the control circuit of the A/C compressor clutch relay and the coil side voltage supply circuit of the A/C compressor clutch relay.
  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 15

15

Does the test lamp remain illuminated with each command?

--

Go to Step 22

Go to Step 21

16
  1. Turn OFF the ignition.
  2. Disconnect the A/C compressor clutch relay.
  3. Probe the switch side voltage supply circuit of the A/C compressor clutch relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 17

Go to Step 25

17
  1. Connect a 10-amp fused jumper wire between the switch side voltage circuit of the A/C compressor clutch relay and the A/C compressor clutch supply voltage circuit of the A/C compressor clutch.
  2. Turn ON the ignition, with the engine OFF.

Does the A/C compressor clutch engage?

--

Go to Step 28

Go to Step 23

18

Test the ignition 3 voltage circuit of the HVAC control module for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 20

19

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 27

20

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 30

21

Test the control circuit of the A/C compressor clutch relay for an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 31

22

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 31

23

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 24

24

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 29

25

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

Did you complete the repair?

--

Go to Step 37

--

26

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

Did you complete the repair?

--

Go to Step 37

--

27

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 32

28

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 33

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 Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 34

30

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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 37

Go to Step 35

31

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

Did you find and correct the condition?

--

Go to Step 37

Go to Step 36

32

Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

--

Go to Step 37

--

33

Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

--

Go to Step 37

--

34

Replace the A/C compressor clutch coil. Refer to A Air Conditioning Clutch Coil Removal and Air Conditioning Clutch Coil Installation in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

--

Go to Step 37

--

35

Replace the HVAC control module. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 37

--

36

Important:  Perform the programming procedure for the PCM.

Replace the PCM. Refer to one of the following procedures:

    •  Powertrain Control Module Replacement in Engine Controls-3.1L
    •  Powertrain Control Module Replacement in Engine Controls-3.8L

Did you complete the replacement?

--

Go to Step 37

--

37

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 4