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 in Vehicle DTC Information

2

1. Start the engine.
2. Observe the instrument panel 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 in Engine Cooling

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 in Wiring Systems

Go to Step 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 in Heating, Ventilation and Air Conditioning

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

1. Start the engine.
2. With a scan tool, observe the A/C Request Signal parameter in the 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

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

1. Turn OFF the ignition.
2. Test the A/C request signal circuit for the following:

•	A short to voltage

•	A high resistance

•

An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 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

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

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

Does the test lamp remain illuminated with each command?

Go to Step 21

Go to Step 20

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

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

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

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 17

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

Did you find and correct the condition?

Go to Step 39

Go to Step 30

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

Does the value measure near battery voltage?

Go to Step 31

Go to Step 19

Test the A/C request signal circuit for the following:

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 39

Go to Step 30

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

Did you find and correct the condition?

Go to Step 39

Go to Step 32

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

Did you find and correct the condition?

Go to Step 39

Go to Step 32

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

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 24

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

Did you find and correct the condition?

Go to Step 39

Go to Step 27

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 29

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 39

--

Repair the coil side of the 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 39

--

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 33

Inspect for poor connections at the A/C compressor clutch relay. 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 39

Go to Step 34

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 35

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 39

Go to Step 36

Inspect for poor connections at the harness connector of the BCM. 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 39

Go to Step 37

Inspect for poor connections at the harness connector of the powertrain control module (PCM). 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 39

Go to Step 38

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 39

--

Replace the A/C compressor clutch relay.

Did you complete the replacement?

Go to Step 39

--

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

Did you complete the replacement?

Go to Step 39

--

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

Did you complete the replacement?

Go to Step 39

--

Important: Perform the reprogramming procedure for the BCM. Refer to Service Programming System (SPS) in Programming.

Replace the BCM. Refer to Body Control Module Replacement in Computer/Integrating Systems.

Did you complete the replacement?

Go to Step 39

--

Important: Perform the reprogramming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.5L.

Did you complete the replacement?

Go to Step 39

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 4

0.01

0

0.20

9

0.29

27

0.33

30

3.76

336

4.65

428

4.69

432

4.92

453

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 in Vehicle DTC Information

2

1. Start the engine.
2. Observe the instrument panel 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 in Engine Cooling

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 in Wiring Systems

Go to Step 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 in Heating, Ventilation and Air Conditioning

1. Turn ON the ignition, with the engine OFF.
2. With a DMM, observe the A/C High Side Pressure Sensor Signal Voltage parameter.
3. Compare the DMM A/C High Side Pressure Sensor Signal Voltage parameter to the high side pressure values on the J 43600 . Refer to Diagnostic Aids above for DMM voltage to psi conversion values.

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

1. Start the engine.
2. With a scan tool, observe the A/C Request Signal parameter in the 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

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

1. Turn OFF the ignition.
2. Test the A/C request signal circuit for the following:

•	A short to voltage

•	A high resistance

•

An open

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 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

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

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

Does the test lamp remain illuminated with each command?

Go to Step 21

Go to Step 20

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

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

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

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 17

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

Did you find and correct the condition?

Go to Step 39

Go to Step 30

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

Does the value measure near battery voltage?

Go to Step 31

Go to Step 19

Test the A/C request signal circuit for the following:

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 39

Go to Step 30

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

Did you find and correct the condition?

Go to Step 39

Go to Step 32

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

Did you find and correct the condition?

Go to Step 39

Go to Step 32

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

Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 24

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

Did you find and correct the condition?

Go to Step 39

Go to Step 27

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 29

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 39

--

Repair the coil side of the 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 39

--

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 33

Inspect for poor connections at the A/C compressor clutch relay. 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 39

Go to Step 34

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 39

Go to Step 35

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 39

Go to Step 36

Inspect for poor connections at the harness connector of the BCM. 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 39

Go to Step 37

Inspect for poor connections at the harness connector of the powertrain control module (PCM). 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 39

Go to Step 38

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 39

--

Replace the A/C compressor clutch relay.

Did you complete the replacement?

Go to Step 39

--

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

Did you complete the replacement?

Go to Step 39

--

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

Did you complete the replacement?

Go to Step 39

--

Important: Perform the reprogramming procedure for the BCM. Refer to Service Programming System (SPS) in Programming.

Replace the BCM. Refer to Body Control Module Replacement in Computer/Integrating Systems.

Did you complete the replacement?

Go to Step 39

--

Important: Perform the reprogramming procedure for the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 2.2L.

Did you complete the replacement?

Go to Step 39

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 4