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NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [L3]

BME010300103262

24 | A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY.
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DESCRIPTION | A/C compressor magnetic clutch does not disengage.
POSSIBLE CAUSE | • Stuck engagement A/C compressor magnetic clutch • A/C relay is stuck closed. • Short to GND between A/C switch and PCM • Short to GND circuit between A/C relay and PCM • A/C relay to magnetic clutch circuit shorted to battery power

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Connect the WDS or equivalent to the DLC-2. Retrieve any continuous memory, KOEO and KOER DTCs. Are there any DTCs displayed? | Yes | DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | No DTC is displayed: Go to the next step.
2 | Start the engine and run it at idle. Turn the A/C switch on. Remove the A/C relay. Does the A/C magnetic clutch disengage? | Yes | Inspect for the following: • A/C relay is stuck closed. • Short to GND circuit between A/C relay and PCM terminal 4O. If both items normal, go to the next step.
No | Inspect if circuit between the A/C relay and the magnetic clutch shorts to battery power circuit. If circuit is normal, inspect the magnetic clutch stuck engagement or clearance.
3 | Connect the WDS or equivalent to the DLC-2. Access AC_REQ PID. Start the engine and turn the A/C switch on. Read AC_REQ PID while disconnecting the refrigerant pressure switch connector.

  Note

  • AC_REQ PID should read OFF when disconnecting the connector. If AC_REQ PID reading remains ON, short to GND circuit may be present.
Does AC_REQ PID reading remain ON?

Yes
Inspect for short to GND circuit between the refrigerant pressure switch and PCM terminal 1AC.
No | Go to the next step.
4 | Reconnect the refrigerant pressure switch connector. Read AC_REQ PID while turning off the A/C switch.

  Note

  • AC_REQ PID should read OFF when turning the A/C switch off. If AC_REQ PID reading remains ON, short to GND circuit may be present.
Does AC_REQ PID reading remain ON?

Yes
Inspect the following:
• Short to GND circuit between A/C switch and A/C amplifier
• Short to GND circuit between A/C amplifier and refrigerant pressure switch
No | Inspect for stuck closed A/C switch.
5 | Verify test results. • If normal, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM.