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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 HVAC Compressor Clutch Does Not Disengage

Test Description

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

  1. These actions will disable the HVAC control assembly output to powertrain control module (PCM).

    2.

  2. This step checks the A/C Request Signal parameter to see if the PCM is interpreting an A/C request.

    3.

  3. Ensure that both A/C request signal circuits of the A/C high pressure switch are tested for listed conditions.

    4.

  4. The A/C Request Signal parameter is Yes. The A/C request signal circuits both are not shorted to ground. This step verifies that the A/C high pressure switch is not shorted internally to ground.

Step

Action

Values

Yes

No

Schematic Reference : HVAC Schematics

DEFINITION: The A/C compressor clutch will not disengage when an A/C request is made and when a Powertrain DTC is not set.

1

Did you review the HVAC operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms - HVAC Systems - Manual

2
  1. Start the engine.
  2. Place the blower motor switch in the OFF position.
  3. Place the A/C request switch in the OFF position.

Does the A/C compressor operate?

--

Go to Step 3

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

3

With a scan tool, observe the A/C Request Signal parameter in the Powertrain Data List.

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

--

Go to Step 4

Go to Step 6

4

Test the A/C request signal circuit 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 17

Go to Step 5

5
  1. Turn OFF the ignition.
  2. Disconnect the A/C high pressure switch.
  3. Start the engine.
  4. With a scan tool, observe the A/C Request Signal parameter.

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

--

Go to Step 12

Go to Step 11

6

Remove the A/C compressor clutch relay.

Does the A/C compressor clutch turn OFF?

--

Go to Step 7

Go to Step 9

7

Measure the resistance between the switched terminals on the A/C compressor clutch relay.

Does the resistance measurement equal the specified value?

∞

Go to Step 8

Go to Step 10

8

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 17

Go to Step 12

9

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

Did you find and correct the condition?

--

Go to Step 17

Go to Step 14

10

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 17

Go to Step 13

11

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 17

Go to Step 15

12

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 17

Go to Step 16

13

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

Did you complete the replacement?

--

Go to Step 17

--

14

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

Did you complete the replacement?

--

Go to Step 17

--

15

Important: Perform the calibration procedure for the HVAC control module.

Replace the HVAC control module. Refer to Heater and Air Conditioning Control Replacement .

Did you complete the replacement?

--

Go to Step 17

--

16

Important: Program the PCM.

Replace the PCM. Refer to one of the following procedures:

    •  Powertrain Control Module Replacement in Engine Controls-4.3L
    •  Powertrain Control Module Replacement in Engine Controls-4.8L, 5.3L, and 6.0L
    •  Powertrain Control Module Replacement in Engine Controls-8.1L

Did you complete the replacement?

--

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3