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Makes 🢒 Chevrolet 🢒 1999 🢒 Corvette 🢒 Body and Accessories 🢒 Data Link Communications 🢒 HVAC Compressor Clutch Does Not Engage

A/C Compressor Clutch Does Not Engage <<C60>>

Step

Action

Value(s)

Yes

No

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

1

Were you sent here from the HVAC System Check (C60)?

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Go to Step 2

Go to HVAC System Check

2
  1. Turn the ignition switch to the OFF position.
  2. Install both the high and low A/C refrigerant pressure gages.
  3. Read the refrigerant pressure with the engine off.
    4. • Refrigerant pressure in the high and low sides should equal each other after the A/C system has come to rest.
    • Refrigerant pressure will fluctuate depending on ambient temperature.
    • Proper clutch operation depends on correct refrigerant charge, low refrigerant charge will shut off A/C compressor operation.

Is the high and low side refrigerant pressures below the specified value?

345 kPa (50 psi)

Go toLeak Testing

Go to Step 3

3

Is the high and low side refrigerant pressures above the specified value?

690 kPa (100 psi)

Go to Step 4

Go to Step 5

4

Evacuate and recharge the A/C system according to proper refrigerant fill specifications. Refer to Refrigerant Recovery and Recharging .

Has the A/C system been recharged properly?

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Go to HVAC System Check

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5

Check the A/C MiniFuse ® #24 for an open circuit.

Is the fuse open?

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Go to Step 6

Go to Step 7

6

Locate and repair a short to ground in CKT 59 between the underhood electrical center and the A/C compressor clutch connector.

Is the repair complete?

--

Go to HVAC System Check

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7
  1. Remove the A/C CLU Micro Relay #34 from the underhood electrical center.
  2. Disconnect the A/C compressor clutch connector.
  3. Connect a fused jumper between the ignition feed terminal for the switch side of the A/C CLU Micro Relay #34 and the terminal used to feed CKT 59 in the underhood electrical center.
  4. Connect a DMM between the A/C compressor clutch connector terminal A and ground.
  5. Turn the ignition switch to the ON position.
  6. Measure the available voltage at the A/C compressor clutch connector terminal A.

Is the voltage within the specified values?

10.0-14.0V

Go to Step 9

Go to Step 8

8

Locate and repair an open or a high resistance in CKT 59.

Is the repair complete?

--

Go to HVAC System Check

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9

Using a DMM, measure for continuity between terminal B of the A/C compressor clutch connector and ground.

Is the resistance to ground less than the specified value?

0.5ohms

Go to Step 11

Go to Step 10

10

Locate and repair an open or a high resistance in CKT 150.

Is the repair complete?

--

Go to HVAC System Check

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11
  1. Disconnect the powertrain control module (PCM) connector C1.
  2. Reinstall the A/C CLU Micro Relay #34.
  3. Connect a fused jumper between the PCM connector C1 terminal 39 and ground.
  4. Turn the ignition switch to the ON position.
  5. Using a DMM, measure the voltage at the A/C compressor clutch connector terminal A.

Is the voltage within the specified values?

10.0-14.0V

Go to Step 12

Go to Step 13

12
  1. Remove the fused jumper from the PCM connector C1 terminal 39 and ground.
  2. Reconnect the A/C compressor clutch connector.
  3. Reinstall the fused jumper between the PCM connector C1 terminal 39 and ground.
  4. Turn the ignition switch to the ON position.

Does the A/C compressor clutch engage?

--

Go to Cooling Insufficient - Air Conditioning (A/C) System

Go to Step 23

13
  1. Turn the ignition switch to the OFF position.
  2. Remove the A/C CLU Micro Relay #34.
  3. Using a DMM, measure for continuity between the PCM connector C1 terminal 39 and the CKT 459 terminal of the underhood electrical center which is used for the A/C CLU Micro Relay #34.

Is CKT 459 continuous between these two terminals?

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Go to Step 15

Go to Step 14

14

Locate and repair an open or a high resistance in CKT 459.

Is the repair complete?

--

Go to HVAC System Check

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15

Replace the A/C CLU Mini Relay #34 and retest the A/C system.

Does replacing the A/C CLU Mini Relay #34 correct the concern?

--

Go to HVAC System Check

Go to Step 16

16
  1. Disconnect the HVAC Control Assembly connector C1.
  2. Connect a DMM between the PCM connector C1 terminal 47 and the HVAC Control Assembly connector C1 terminal B.
  3. Measure CKT 762 for continuity between these two connectors.

Is CKT 762 continuous?

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Go to Step 18

Go to Step 17

17

Locate and repair an open or a high resistance in CKT 762.

Is the repair complete?

--

Go to HVAC System Check

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18
  1. Connect a DMM between the PCM connector C1 terminal 47 and ground.
  2. Measure CKT 762 for continuity to ground.

Is CKT 762 continuous to ground?

--

Go to Step 19

Go to Step 20

19

Locate and repair a short to ground in CKT 762.

Is the repair complete?

--

Go to HVAC System Check

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20
  1. Disconnect the DMM.
  2. Reconnect all connectors back to their respective modules.
  3. Install the scan tool to the diagnostic link connector.
  4. Start the engine and allow it to idle in Park.
  5. Select the area of the scan tool which will read HVAC button output status.
  6. Depress the A/C button on/off several times.

Does the scan tool read the A/C request being sent by the HVAC Control Assembly?

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Go to Step 21

Go to Step 22

21

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

Is the repair complete?

--

Go to HVAC System Check

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22

Replace the HVAC Control Assembly. Refer to Control Assembly Replacement .

Is the repair complete?

--

Go to HVAC System Check

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23

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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