GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Silhouette Ext. 🢒 Body and Accessories 🢒 Wiring Systems 🢒 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

Were you sent here from the HVAC System Check?

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Go to Step 2

Go to HVAC System Check

2
  1. Disconnect the Powertrain Control Module (PCM) connector C2.
  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 Replacement/Programming in Engine Controls.

Is the repair complete?

--

Go to HVAC System Check

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4
  1. Disconnect the A/C CLU Micro relay #13 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 C2 still disconnected.
  3. A/C CLU Micro relay #13 still removed from the underhood electrical center.
  4. Connect a J 39200 between the Powertrain Control Module (PCM) connector C2 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

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7

Replace the A/C CLU micro relay #13.

Is the repair complete?

--

Go to HVAC System Check

--

8
  1. Powertrain Control Module (PCM) connector C2 still disconnected.
  2. A/C CLU Micro relay #13 still removed from the underhood electrical center.
  3. Disconnect the A/C compressor clutch connector.
  4. Connect a J 39200 between the A/C compressor clutch connector connector (CKT 59) and ground.
  5. Turn the ignition switch to the ON position.
  6. 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 Plate/Hub Assembly Replacement .

Is the repair complete?

--

Go to HVAC System Check

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