NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [L8, LF]

id0103a0803000

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 | • A/C relay is stuck closed • Short to ground in wiring harness between A/C switch and PCM • Short to power supply in wiring harness between A/C relay and magnetic clutch • Magnetic clutch stuck engagement or clearance • Short to ground in wiring harness between A/C switch and A/C amplifier • Short to ground in wiring harness between A/C amplifier and refrigerant pressure switch • Short circuit to battery power in A/C relay to magnetic clutch • A/C switch is stuck closed • PCM malfunction

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Connect the M-MDS to the DLC-2. Perform the KOEO/KOER self test and the DTC Reading Procedure. (See KOEO/KOER SELF TEST [L8, LF].) (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Are any DTCs present? | Yes | Go to the appropriate DTC inspection. (See DTC TABLE [L8, LF].)
No | Go to the next step.
2 | Start the engine and idle it. Turn the A/C switch on. Remove the A/C relay. Does the A/C magnetic clutch disengage? | Yes | Inspect the following: • A/C relay is stuck closed • Short to ground in wiring harness between A/C relay and PCM terminal 1I Repair or replace the malfunctioning part according to the inspection results, if necessary. If both items are normal: • Go to the next step.
No | Inspect the wiring harness between the A/C relay and magnetic clutch for short to power supply. If the circuit has a malfunction: • Repair or replace the suspected wiring harness. If the circuit is normal: • Inspect for magnetic clutch stuck engagement or clearance. • Repair or replace the malfunctioning part according to the inspection results.
3 | Connect the M-MDS to the DLC-2. Perform the PID/DATA Monitor and Record Procedure and access the AC_REQ PID. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Start the engine and turn the A/C switch on. Monitor the AC_REQ PID while disconnecting refrigerant pressure switch connector. Note • AC_REQ PID should read Off when disconnecting connector. If AC_REQ PID remains On, short to ground may be present. Does the AC_REQ PID remain On? | Yes | Inspect the wiring harness between refrigerant pressure switch and PCM terminal 1AU for short to ground. Repair or replace the suspected wiring harness, if necessary.
No | Go to the next step.
4 | Reconnect the refrigerant pressure switch connector. Perform the PID/DATA Monitor and Record Procedure and access the AC_REQ PID. (See ON-BOARD DIAGNOSTIC TEST [L8, LF].) Monitor the AC_REQ PID while turning off A/C switch. Note • AC_REQ PID should read Off when turning A/C switch off. If AC_REQ PID remains On, short to ground may be present. Does the AC_REQ PID remain On? | Yes | Inspect the following: • Short to ground in wiring harness between the A/C switch and A/C amplifier • Short to ground in wiring harness between the A/C amplifier and refrigerant pressure switch Repair or replace the suspected wiring harness, if necessary.
No | Inspect for stuck closed A/C switch. Repair or replace the malfunctioning part according to the inspection results.
5 | Verify test results. • If normal, return to diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [L8, LF].) • If malfunction remains, inspect related Service information perform repair or diagnosis. ― If vehicle repaired, troubleshooting completed. ― If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)