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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 Rendezvous - FWD 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 HVAC Compressor Clutch Does Not Engage

Diagnostic Aids

The A/C system can be engaged by either pressing the driver temperature switch or during automatic operation. The A/C display will illuminate on the HVAC control module display board when the driver temperature switch is pressed. The control module sends a class 2 A/C request message to the body control module (BCM). The BCM then sends the request to the powertrain control module (PCM). The PCM then grounds the A/C relay control circuit switching the relays contacts sending B+ to the A/C compressor. The HVAC system uses a scroll compressor that incorporates a thermal switch that opens once the compressor temperature is more than 155°C (311°F). The thermal switch is a non-serviceable item.

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 121°C (250°F). The engine coolant indicator will illuminate at this temperature.

  1. Pressing the center of the left side driver temperature control switch and setting the air temperature control switch in a cold setting activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, bi-level mode is used for consistent testing.

    2.

  2. 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

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 review the HVAC operation and perform the necessary inspections?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

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 4

3
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Body Control DTC List

Does a DTC B1000 code set?

Go to Diagnostic Trouble Code (DTC) List in Body Control System

Go to Step 4

4

Important: For A/C compressor operation, 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. Press the drivers side temperature control switch.
  4. Place the drivers side temperature control 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 5

5
  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 switch.
  5. Install the J 43600 ACR 2000 Air Conditioning Service Center.
  6. Record the ambient air temperature at the vehicle.
  7. Record readings of the low and high side STATIC pressures.
  8. Compare the low and 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 low and high side pressure values within the allowable limits for the recorded ambient air temperature, and within 103 kPa (15 psi) of each other?

Go to Step 6

Go to Leak Testing in Heating, Ventilation and Air Conditioning

6
  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 data list.
  3. Compare the A/C high side pressure on the scan tool to the high side pressure value on the ACR 2000.

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

Go to Step 7

Go to Step 17

7

Important: The HVAC control module is inoperative when the module does not respond to any operator control requests.

Is the HVAC control module inoperative?

Go to Step 16

Go to Step 8

8
  1. Start the engine.
  2. With a scan tool, observe the A/C Request Signal parameter in the Powertrain data list.
  3. Place the air temperature switch in the coldest position.
  4. Press the drivers side temperature control switch.

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

Go to Step 9

Go to Step 28

9

With a scan tool, observe the A/C Relay Command parameter in the Powertrain data list.

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

Go to Step 10

Go to Step 29

10

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 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 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 12

Go to Step 24

12
  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 26

Go to Step 13

13

Does the test lamp remain illuminated with each command?

Go to Step 20

Go to Step 19

14
  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 15

Go to Step 23

15
  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 26

Go to Step 21

16

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 35

Go to Step 18

17

Test the ground circuit of the A/C 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 35

Go to Step 25

18

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 35

Go to Step 28

19

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

Did you find and correct the condition?

Go to Step 35

Go to Step 29

20

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 35

Go to Step 29

21

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

Did you find and correct the condition?

Go to Step 35

Go to Step 22

22

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 35

Go to Step 27

23

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 35

--

24

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 35

--

25

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 Connector Repairsin Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 30

26

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 35

Go to Step 31

27

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 Repairsin Wiring Systems.

Did you find and correct the condition?

Go to Step 35

Go to Step 32

28

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

Did you find and correct the condition?

Go to Step 35

Go to Step 33

29

Inspect for poor connections at the harness connector of the powertrain control module (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 35

Go to Step 34

30

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

Did you complete the replacement?

Go to Step 35

--

31

Replace the A/C compressor clutch relay.

Did you complete the replacement?

Go to Step 35

--

32

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

Did you complete the replacement?

Go to Step 35

--

33

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

Did you complete the replacement?

Go to Step 35

--

34

Important:  Perform the reprogramming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-3.4L.

Did you complete the replacement?

Go to Step 35

--

35

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 5