GM Service Manual Online
For 1990-2009 cars only

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 Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Start the engine.
  2. Place the blower motor switch in the maximum speed position.
  3. Ensure the A/C OFF switch is not selected.
  4. Place the left air temperature switch in the coldest position.

Does the A/C compressor operate?

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

Go to Step 3

3

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

Is the engine coolant temperature indicator illuminated?

 

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Install the ACR 2000.
  3. Record the ambient temperature at the vehicle.
  4. Record readings of the low and high side STATIC pressures.
  5. 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 and 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 5

Go to Leak Testing in Heating, Ventilation and Air Conditioning

5

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool observe the A/C refrigerant pressure sensor in the engine, engine cooling data list.
  4. Compare the A/C refrigerant pressure sensor parameter on the scan tool with the ACR 2000 high side pressure value.

Is the scan tool A/C refrigerant pressure sensor parameter and the ACR 2000 pressure value within 15 psi of each other?

 

Go to Step 6

Go to Step 13

6

With a scan tool, view the ambient air temperature in the HVAC system data.

Is the ambient air temperature below 3°C (38F°)?

 

Go to Step 16

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Disconnect the A/C compressor clutch.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the supply voltage circuit of the A/C compressor clutch with a test lamp that is connected to ground.
  5. With a scan tool, command the A/C compressor clutch relay ON.

Does the test lamp illuminate?

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Go to Step 8

Go to Step 9

8

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?

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Go to Step 25

Go to Step 12

9

Test the voltage supply 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?

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Go to Step 25

Go to Step 10

10

  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 battery positive voltage circuit on the switch side of the A/C compressor clutch relay with a test lamp that is connected to ground.

Does the test lamp illuminate?

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Go to Step 11

Go to Step 21

11

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 25

Go to Step 22

12

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?

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Go to Step 25

Go to Step 23

13

  1. Disconnect the A/C pressure sensor.
  2. With a test lamp connected to battery voltage, probe the ground circuit at the A/C pressure sensor connector.

Does the test lamp illuminate?

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Go to Step 17

Go to Step 14

14

Test the ground circuit of the A/C refrigerant pressure sensor 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?

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Go to Step 25

Go to Step 15

15

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?

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Go to Step 25

Go to Step 24

16

Inspect the ambient air temperature sensor circuits for high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 25

Go to Step 19

17

Inspect for poor connections at the harness connector of the A/C 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 25

Go to Step 18

18

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 25

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19

Inspect for poor connections at the harness connector of the ambient air 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 25

Go to Step 20

20

Replace the ambient air temperature sensor. Refer to Ambient Air Temperature Sensor Replacement in Heating, Ventilation and Air Conditioning.

Did you complete the replacement?

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Go to Step 25

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21

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?

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Go to Step 25

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22

Replace the A/C compressor clutch relay.

Did you complete the replacement?

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Go to Step 25

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23

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

Did you complete the replacement?

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Go to Step 25

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24

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

Did you complete the replacement?

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Go to Step 25

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25

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2