GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Montana 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 HVAC Compressor Clutch Does Not Disengage

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

Was the entire HVAC diagnostic system check performed?

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Go to Step 2

Go to Diagnostic System Check

2
  1. Disconnect the Powertrain Control Module (PCM) connector C2.
  2. Turn the ignition switch to the RUN position.

Does the A/C compressor clutch coil disengage?

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Go to Step 3

Go to Step 4

3

Important: Perform the reprogramming procedure for the PCM.

Replace the Powertrain Control Module (PCM). Refer to Powertrain Control Module Replacement/Programming in Engine Controls.

Is the repair complete?

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Go to Step 11

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4
  1. Disconnect the A/C CLU relay from the underhood accessory wiring junction block.
  2. Turn the ignition switch to the RUN position.

Does the A/C compressor clutch coil disengage?

--

Go to Step 5

Go to Step 8

5
  1. Turn the ignition switch to the OFF position.
  2. Connect a DMM between the PCM connector C2 terminal 39 and ground. Refer to Circuit Testing in Wiring Systems.
  3. Measure for continuity in circuit 459 to ground. Refer to Circuit Testing in Wiring Systems.

Is CKT 459 continuous to ground?

--

Go to Step 6

Go to Step 7

6

Repair a short to ground in CKT 459 between the underhood accessory wiring junction block and the PCM connector C2. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

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Go to Step 11

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7

Replace the A/C CLU relay. Refer to Compressor Relay Replacement .

Is the repair complete?

--

Go to Step 11

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8
  1. Disconnect the A/C compressor clutch coil connector. Refer to Air Conditioning Clutch Coil Removal in HVAC - Heating, Ventilation, and Air Conditioning.
  2. Connect a DMM between the A/C compressor clutch coil connector terminal B and ground. Refer to Circuit Testing in Wiring Systems.
  3. Turn the ignition switch to the RUN position.
  4. Measure for voltage on CKT 59.

Is voltage present on CKT 59?

--

Go to Step 9

Go to Step 10

9

Repair a short to B+ on CKT 59 between the underhood accessory wiring junction block and the A/C compressor clutch coil. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 11

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10

Replace the A/C compressor clutch coil. Refer to Air Conditioning Clutch Coil Replacement .

Is the repair complete?

--

Go to Step 11

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11
  1. Turn the ignition switch to the OFF position.
  2. Reconnect all connectors/components disconnected.

Have all repairs been made?

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Go to Diagnostic System Check

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