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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 SSR 🢒 Body and Accessories 🢒 Wiring Systems 🢒 HVAC Compressor Clutch Does Not Engage

Diagnostic Aids

The A/C compressor clutch will not engage under the following conditions:

    • The A/C high side line pressure is over 2413 kPa (350 psi).
    • Throttle angle is at 100 percent.
    • A/C compressor temperature switch contacts are open
    • Engine speed is more than 5500 RPM.
    • Engine coolant temperature (ECT) is more than 123°C (253°F).
    • Evaporator core temperature is less than 0°C (32°F).
    • Engine is idling at a low unstable RPM.

Test Description

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

  1. The A/C compressor output is disabled if the engine is idling at a low unstable RPM.

    2.

  2. The A/C compressor relay output is disabled if engine coolant temperature is above 123°C (253°F). The check gages indicator will illuminate at this temperature.

    3.

  3. These actions will enable the A/C compressor to operate.

    4.

  4. This test ensures that there is sufficient refrigerant in the A/C system. The specific values come from the A/C System Performance Test in Heating, Ventilation and Air Conditioning.

Step

Action

Values

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?

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Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Manual

2

  1. Start the engine.
  2. Set the parking brake.
  3. Place the vehicle in drive and allow the engine to idle.
  4. Observe the engine RPM.

Does the engine idle at a steady RPM?

--

Go to Step 3

Go to Rough, Unstable, or Incorrect Idle and Stalling in Engine Controls - 4.8L, 5.3L, and 6.0L

3

  1. Start the engine.
  2. Observe the check gages indicator.

Is the check gages indicator illuminated?

--

Go to Step 4

Go to Step 5

4
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool observe the ECT parameter in the Powertrain Engine Data 1 data list.

Does the ECT parameter display greater than the specified value?

123°C (253°F)

Go to Engine Overheating in Engine Cooling

Go to Step 5

5

Important: For A/C compressor operation, the evaporator core temperature must be above 0°C (32°F).

  1. Start the engine.
  2. Place the blower motor switch in the low speed position.
  3. Place the A/C request switch to the ON position.
  4. Place the mode switch to the vent position.

Does the A/C compressor clutch engage?

--

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

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the A/C Request Signal parameter in the Roof/Door Module (RDM) data list.

Does the scan tool indicate that the A/C Request Signal parameter displays Yes?

--

Go to Step 7

Go to Step 12

7

  1. Park the vehicle inside or out of direct sunlight.
  2. Open the window in order to ventilate the interior of the vehicle.
  3. Turn OFF the ignition.
  4. If the A/C system was operating, then wait for approximately 2 minutes.
  5. Install J 43600 .
  6. Record the ambient temperature at the vehicle.
  7. Record readings of the low and high side STATIC pressures.
  8. Compare the low and the high side pressure values with the allowable limits for the recorded ambient air temperature.

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

Above 16°C (60°F) 345 kPa (50 psi)

Above 24°C (75°F) 483 kPa (70 psi)

Above 33°C (90°F) 690 kPa (100 psi)

Go to Step 8

Go to Leak Testing in Heating, Ventilation and Air Conditioning

8
  1. Disconnect the A/C compressor relay.
  2. Probe the battery positive voltage circuit of the A/C compressor clutch relay with a test lamp connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 18

9

Probe the ignition 3 voltage circuit of the A/C compressor clutch relay with a test lamp connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 19

10
  1. Probe the A/C compressor clutch control circuit of the A/C compressor clutch relay with a test lamp connected to battery positive voltage.
  2. With a scan tool command the A/C Relay output control to ON.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 11

11

Connect a 10-amp fused jumper between the battery positive voltage circuit and the A/C compressor clutch supply voltage circuit of the A/C compressor clutch relay.

Does the A/C compressor clutch engage?

--

Go to Step 20

Go to Step 15

12
  1. Disconnect the evaporator temperature sensor.
  2. Probe the A/C request signal circuit of the HVAC control module with a test lamp connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 13

Go to Step 16

13
  1. Connect a 3-amp fused jumper between the A/C request signal circuit of the HVAC control module and the A/C request signal circuit of the RDM.
  2. Observe the A/C Request Signal parameter.

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

--

Go to Step 21

Go to Step 17

14

Test the A/C compressor clutch relay control circuit of the A/C compressor clutch relay 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 32

Go to Step 23

15

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 32

Go to Step 24

16

Test the A/C request signal circuit of the HVAC control module for a short to ground, a high resistance and for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 32

Go to Step 25

17

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

Did you find and correct the condition?

--

Go to Step 32

Go to Step 22

18

Repair the battery positive voltage circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

19

Repair the ignition 3 voltage circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

20

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 32

Go to Step 26

21

Inspect for poor connections at the evaporator temperature 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 32

Go to Step 28

22

Inspect for poor connections at the RDM. 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 32

Go to Step 27

23

Inspect for poor connections at the 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 32

Go to Step 29

24

Inspect for poor connections at 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 32

Go to Step 30

25

Inspect for poor connections at 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 32

Go to Step 31

26

Replace the A/C compressor clutch relay.

Did you complete the replacement?

--

Go to Step 32

--

27

Important: Perform the setup procedure for the RDM.

Replace the RDM. Refer to Folding Top Control Module Replacement in Roof.

Did you complete the replacement?

--

Go to Step 32

--

28

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

Did you complete the replacement?

--

Go to Step 32

--

29

Important: Program the PCM.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L.

Did you complete the replacement?

--

Go to Step 32

--

30

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 32

--

31

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

Did you complete the replacement?

--

Go to Step 32

--

32

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 5