NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZI-3.7]

id0103d2803000

24

A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY.

DESCRIPTION

A/C compressor magnetic clutch does not disengage.

POSSIBLE CAUSE

•  A/C compressor magnetic clutch engagement is stuck.

•  A/C relay is stuck closed.

•  Short to GND in wiring harness between A/C switch and PCM

•  Short to GND in wiring harness between A/C relay and PCM

•  Short circuit to battery power in A/C relay to magnetic clutch

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

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Connect the M-MDS to the DLC-2. Turn the ignition switch to the ON position (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7].)
1		No	No DTC is displayed: 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 for the following: • A/C relay is stuck closed. • Short to GND in wiring harness between A/C relay and PCM terminal 1N. If both items normal, go to the next step.
2		No	Inspect if circuit between the A/C relay and magnetic clutch shorts to battery power circuit. If the circuit is normal, inspect the magnetic clutch for stuck engagement or clearance.
3	Disconnect refrigerant pressure switch connector. Start the engine and turn A/C switch on. Note • A/C should not work when disconnecting connector. If A/C remains working, short to GND circuit may be present. Does the A/C remain working?	Yes	Inspect for short to GND in wiring harness between refrigerant pressure switch and PCM terminal 1R.
3		No	Go to the next step.
4	Reconnect refrigerant pressure switch connector. Turn off A/C switch. Note • A/C should not work when turning A/C switch off. If A/C remains working, short to GND circuit may be present. Does A/C remain working?	Yes	Inspect following: • Short to GND in wiring harness between A/C switch and A/C amplifier • Short to GND circuit between A/C amplifier and refrigerant pressure switch
4		No	Inspect whether A/C switch is stuck closed.
5	• Verify test results. ― If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].) ― If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)