NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR 2.0, MZR 2.5]

id0103e1803000

24

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

DESCRIPTION

•  The A/C compressor magnetic clutch does not disengage.

POSSIBLE CAUSE

•  PCM, instrument cluster or climate control unit DTC is stored.

•  A/C compressor magnetic clutch engagement is stuck

•  A/C relay is stuck closed

•  Short to power supply in wiring harness between A/C relay and magnetic clutch

•  Communication error between instrument cluster and climate control unit

•  Communication error between PCM and instrument cluster

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

•  Short to ground in wiring harness between climate control unit terminal 2P and instrument cluster (Manual air conditioner)

•  Climate control unit malfunction

•  PCM malfunction

24	A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY
DESCRIPTION	• The A/C compressor magnetic clutch does not disengage.
POSSIBLE CAUSE	• PCM, instrument cluster or climate control unit DTC is stored. • A/C compressor magnetic clutch engagement is stuck • A/C relay is stuck closed • Short to power supply in wiring harness between A/C relay and magnetic clutch • Communication error between instrument cluster and climate control unit • Communication error between PCM and instrument cluster • Short to ground in wiring harness between A/C relay and PCM • Short to ground in wiring harness between climate control unit terminal 2P and instrument cluster (Manual air conditioner) • Climate control unit malfunction • PCM malfunction

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Retrieve the PCM, instrument cluster and climate control unit DTCs. (See ON-BOARD DIAGNOSTIC TEST [MZR 2.0, MZR 2.5].) (See DTC INSPECTION [INSTRUMENT CLUSTER].) (See DTC DISPLAY [FULL-AUTO AIR CONDITIONER].) Are any DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE [MZR 2.0, MZR 2.5].) (See DTC TABLE [INSTRUMENT CLUSTER].) (See DTC TABLE [FULL-AUTO AIR CONDITIONER].)
1		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	Go to Step 4.
2		No	Go to the next step.
3	A/C relay is removed. Switch the ignition to off. Disconnect the A/C compressor connector. Switch the ignition to ON (engine off). Measure the voltage between A/C compressor terminal A (wiring harness-side) and body ground. Is the voltage B+?	Yes	Repair or replace the wiring harness for a possible short to power supply.
3		No	Replace the A/C compressor (A/C magnetic clutch engagement stuck). (See A/C COMPRESSOR REMOVAL/INSTALLATION.)
4	Inspect the A/C relay. (See RELAY INSPECTION.) Is there any malfunction?	Yes	Replace the A/C relay.
4		No	Go to the next step.
5	Access the ACCS PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 2.0, MZR 2.5].) Start the engine and idle it. Turn the A/C switch on and off with blower switch is on. Is the ACCS PID value always ON?	Yes	Manual air conditioner: • Go to the next step. Full-auto air conditioner: • Replace the climate control unit (A/C request signal always on). (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
5		No	Inspect for short to ground in wiring harness between PCM terminal 1I and A/C relay. Repair or replace the malfunctioning part according to the inspection results.
6	Switch the ignition to off. Disconnect the instrument cluster and climate control unit connectors. Inspect for continuity between climate control unit terminal 2P (wiring harness-side) and body ground. Is there continuity?	Yes	Repair or replace the suspected wiring harness.
6		No	Replace the climate control unit (A/C request signal always on). (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
7	• Verify the test results. ― If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0, MZR 2.5].) ― If a malfunction remains, inspect the related Service Information perform repair or diagnosis. • If the vehicle repaired, troubleshooting is completed. • If the vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 2.0, MZR 2.5].)