Schematic Reference: HVAC Schematics

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 Symptoms - HVAC Systems - Manual

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. Place the A/C switch in the ON position.
4. Place the air temperature control 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 3

1. Park the vehicle inside or in the shade.
2. Open the windows in order to ventilate the interior of the vehicle.
3. Turn OFF the ignition.
4. If the A/C system was operating, allow the A/C system to equalize, about 2 minutes.
5. Install the J 39500-B ACR 4.
6. Record the ambient temperature at the vehicle.
7. Record readings of the low and high side STATIC pressures.

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 4

Go to Leak Testing in Heating, Ventilation and Air Conditioning

4

Is the HVAC control module inoperative?

Go to Step 7

Go to Step 5

1. Turn ON the ignition, with the engine OFF.
2. Turn the A/C switch in the ON position.
3. Disconnect the evaporator temperature sensor connector.
4. Probe the request circuit at the evaporator temperature sensor connector with a test lamp that is connected to voltage.

Does the test lamp illuminate?

Go to Step 6

Go to Step 9

1. Turn ON the ignition, with the engine OFF.
2. Disconnect the evaporator temperature sensor connector.
3. Probe the evaporator temperature sensor supply voltage circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 18

Test the battery positive voltage circuit to 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 33

Go to Step 8

Test the ground circuit to the HVAC control module for an 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 33

Go to Step 26

Test the A/C request signal circuit 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 33

Go to Step 26

1. Turn OFF the ignition.
2. Disconnect the A/C compressor clutch relay.
3. Turn ON the ignition, with the engine OFF.
4. Turn the A/C switch in the ON position.
5. Probe the control circuit of the A/C compressor clutch relay with a test lamp that is connected to voltage.

Does the test lamp illuminate?

Go to Step 11

Go to Step 19

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 battery positive voltage 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 20

1. Turn OFF the ignition.
2. Disconnect the A/C compressor clutch relay.
3. Probe the switch side battery positive voltage 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 13

Go to Step 21

1. Turn OFF the ignition.
2. Connect the A/C compressor clutch relay.
3. Turn ON the ignition, with the engine OFF.
4. Turn the A/C switch in the ON position.
5. Probe the compressor clutch voltage supply circuit from the A/C compressor relay, at the A/C high pressure switch with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 15

Go to Step 14

Test the compressor clutch voltage supply circuit between the A/C compressor relay and the high pressure switch 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 33

Go to Step 23

1. Connect a 10 amp fused jumper wire across the high pressure switch connector, for the A/C compressor clutch voltage supply circuit.
2. Turn ON the ignition, with the engine OFF.
3. Turn the A/C switch in the ON position.

Does the A/C compressor clutch engage?

Go to Step 27

Go to Step 16

1. Turn ON the ignition, with the engine OFF.
2. Turn the A/C switch in the ON position.
3. Probe the compressor clutch voltage supply circuit at the compressor, with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 17

Go to Step 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 33

Go to Step 25

Repair the evaporator temperature sensor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

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Test the A/C relay control circuit between the A/C relay and the evaporator temperature sensor 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 33

Go to Step 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 33

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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 33

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Repair the compressor clutch voltage supply circuit between the A/C compressor clutch and the high pressure switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 33

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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 33

Go to Step 28

Inspect for poor connections at the harness connector of the A/C evaporator temperature 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 33

Go to Step 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 33

Go to Step 31

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 33

Go to Step 32

Inspect for poor connections at the harness connector of the A/C high pressure switch. 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 33

Go to Step 30

Replace the A/C compressor clutch relay. Refer to Compressor Relay Replacement .

Did you complete the replacement?

Go to Step 33

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Replace the A/C evaporator temperature sensor. Refer to Evaporator Temperature Sensor Replacement in Heating, Ventilation, and Air Conditioning.

Did you complete the replacement?

Go to Step 33

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

Did you complete the replacement?

Go to Step 33

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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 33

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

Did you complete the replacement?

Go to Step 33

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3