GM Service Manual Online
For 1990-2009 cars only

A/C Compressor Clutch Will Not Disengage <<CJ2>>

Step

Action

Value(s)

Yes

No

DEFINITION: A/C compressor clutch will not disengage when no A/C request has been made and no Powertrain DTC has been set.

1

Were you sent here from the HVAC System Check (CJ2)?

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Go to Step 2

Go to HVAC System Check

2

  1. Disconnect the Powertrain Control Module (PCM) connector C1.
  2. Turn the ignition switch to the ON position.

Does the A/C clutch disengage?

--

Go to Step 3

Go to Step 4

3

Replace the Powertrain Control Module (PCM). Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .

Is the repair complete?

--

Go to HVAC System Check

--

4

  1. Disconnect the A/C CLU Micro relay #34 from the underhood electrical center.
  2. Turn the ignition switch to the ON position.

Does the A/C clutch disengage?

--

Go to Step 5

Go to Step 8

5

  1. Turn the ignition switch to the OFF position.
  2. Powertrain Control Module (PCM) connector C1 still disconnected.
  3. A/C CLU Micro relay #34 still removed from the underhood electrical center.
  4. Connect a DMM between the Powertrain Control Module (PCM) connector C1 terminal 39 and ground.
  5. Measure for continuity in CKT 459 to ground.

Is CKT 459 continuous to ground?

--

Go to Step 6

Go to Step 7

6

Locate and repair a short to ground in CKT 459 between the underhood electrical center and the PCM connector C1.

Is the repair complete?

--

Go to HVAC System Check (CJ2)

--

7

Replace the A/C CLU Micro relay #34.

Is the repair complete?

--

Go to HVAC System Check

--

8

  1. Powertrain Control Module (PCM) connector C1 still disconnected.
  2. A/C CLU Micro relay #34 still removed from the underhood electrical center.
  3. Connect a DMM between the Powertrain Control Module (PCM) connector C1 terminal 14 and ground.
  4. Turn the ignition switch to the ON position.
  5. Measure for voltage on CKT 59.

Is voltage present on CKT 59?

--

Go to Step 9

Go to Step 10

9

Locate and repair a short to battery voltage on CKT 59 between the underhood electrical center and the A/C compressor clutch.

Is the repair complete?

--

Go to HVAC System Check

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10

Replace the A/C compressor clutch. Refer to Compressor Clutch Coil Removal (V7 - Direct Mount) .

Is the repair complete?

--

Go to HVAC System Check

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