GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you review the HVAC compressor controls circuit description and perform the necessary inspections?

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Go to Step 2

Go to Symptoms

2

  1. Place the ignition switch in the OFF position.
  2. Place the mode switch on the heater and A/C controller in the OFF position.
  3. Place the ignition switch in the ON position.
  4. Start and idle the engine.
  5. Observe the A/C compressor clutch for a minimum of 5 minutes.

Is the A/C compressor clutch disengaged?

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Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Place the ignition switch in the LOCK position.
  2. Place the mode switch on the heater and A/C controller in the OFF position.
  3. Inspect the compressor for seizure. Refer to CCOT Air Conditioning (A/C) System Diagnosis .

Is the A/C compressor seized?

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Go to Step 9

Go to Step 4

4

  1. Disconnect heater and A/C controller connector C2.
  2. Disconnect vehicle control module (VCM) connector C3 on a gasoline engine vehicle, or powertrain control module (PCM) connector C1 on a diesel engine vehicle.
  3. Place the ignition switch in the RUN position.
  4. Connect an unpowered test lamp between VCM connector C3 cavity 25, or PCM connector C1 cavity C2, for CKT and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp light?

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Go to Step 10

Go to Step 5

5

Reconnect heater and A/C controller connector C2.

Does the test lamp light?

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Go to Step 11

Go to Step 6

6

  1. Remove the A/C compressor enable relay from the socket in the underhood fuse-relay center.
  2. Disconnect the A/C compressor clutch connector.
  3. Connect a J 35616-200 unpowered test lamp to A/C compressor clutch connector cavity B for CKT 59 (DK GRN) and ground. Refer to Circuit Testing in Wiring Systems.

Does the test lamp light?

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Go to Step 12

Go to Step 7

7

  1. Reconnect vehicle control module (VCM) connector C3 for the gasoline engine vehicle.
  2. Connect a J 39200 digital multimeter (DMM) between underhood fuse-relay center cavity C1 for CKT 459 (DK GRN/WHT) and ground. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

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Go to Step 8

Go to Step 13

8

  1. Disconnect VCM connector C3 on a gasoline engine vehicle, or PCM connector C3 on a diesel engine vehicle.
  2. Connect a J 39200 DMM between underhood fuse-relay center cavity C1 for CKT 459 DK GRN/WHT) and ground. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

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Go to Step 14

Go to Step 15

9

Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement

Does the compressor clutch disengage?

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Go to Step 16

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10

Repair the short to voltage in CKT 2523 (DK GRN/WHT) between VCM connector C3 in gasoline engine vehicles, or PCM connector C1 in diesel engine vehicles, and the heater and A/C controller connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 16

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11

Replace the heater and A/C controller. Refer to Control Assembly Replacement .

Is the repair complete?

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Go to Step 16

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12

Repair the short to voltage in CKT 59 (DK GRN) between the underhood fuse-relay center and the A/C compressor clutch connector. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 16

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13

Replace the A/C compressor enable relay.

Is the repair complete?

--

Go to Step 16

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14

Repair the short to ground in CKT 459 (DK GRN/WHT) between VCM connector C3 on a gasoline engine vehicle, or PCM connector C3 on a diesel engine vehicle and the underhood fuse-relay center. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 16

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15

Replace the VCM in a gasoline engine vehicle or the PCM in a diesel engine vehicle. Refer to the appropriate procedure:

    •  VCM Replacement/Programming in Engine Controls (4.3L)
    •  VCM Replacement/Programming in Engine Controls (5.0L, 5.7L)
    •  Powertrain Control Module Replacement/Programming in Engine Controls (6.5L)
    •  VCM Replacement/Programming in Engine Controls (7.4L)

Is the repair complete?

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Go to Step 16

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16

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3