NO.28 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD 2.2]SM2444564
NO.28 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD 2.2]

id0103f3843100

28

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

DESCRIPTION
• A/C compressor magnetic clutch does not disengage.
POSSIBLE CAUSE
• PCM, instrument cluster or climate control unit DTC is stored
• Short to power supply in wiring harness between A/C relay and magnetic clutch
• A/C compressor magnetic clutch engagement is stuck
• A/C relay malfunction
• Short to ground in wiring harness between A/C relay and PCM
• Short to ground in wiring harness between climate control unit terminal J and BCM terminal 3L (Manual air conditioner)
• Climate control unit malfunction
• PCM malfunction

Diagnostic Procedure

STEP

INSPECTION

RESULTS

ACTION
1
Switch the ignition ON (Engine off).
Retrieve PCM, BCM, instrument cluster and climate control unit DTCs.
(See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].)
(See DTC INSPECTION [BCM].)
(See DTC INSPECTION [INSTRUMENT CLUSTER].)
(See DTC DISPLAY.)
Are there any DTCs displayed?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR-CD 2.2].)
(See DTC TABLE [BCM].)
(See DTC TABLE [INSTRUMENT CLUSTER].)
(See DTC TABLE.)
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 5.
No
Go to the next step.
3
Switch the ignition off.
Disconnect the A/C compressor connector.
Start the engine and idle it.
Does the A/C magnetic clutch disengage?
Yes
Inspect and repair for short to power supply between A/C relay terminal C and A/C compressor connector.
No
Go to the next step.
4
Verify that the A/C magnetic clutch clearance.
(See MAGNETIC CLUTCH ADJUSTMENT [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH ADJUSTMENT [MANUAL AIR CONDITIONER].)
Is the magnetic clutch clearance normal?
Yes
Inspect and repair A/C magnetic clutch for stuck.
(See MAGNETIC CLUTCH INSPECTION [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH INSPECTION [MANUAL AIR CONDITIONER].)
(See MAGNETIC CLUTCH DISASSEMBLY/ASSEMBLY [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH DISASSEMBLY/ASSEMBLY [MANUAL AIR CONDITIONER].)
No
Adjust the magnetic clutch clearance.
5
Access the PCM PID AC_REQ using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR-CD 2.2].)
Monitor the AC_REQ PID while turning on and off the air conditioner by switching the control panel.
Is the AC_REQ PID always ON?
Yes
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].)
Manual air conditioner:
• Go to the next step.
No
Go to Step 7.
6
Switch the ignition off.
Disconnect the climate control unit connector.
Verify continuity between climate control unit connector terminal J (24-pin) and body ground.
Is there continuity?
Yes
Repair for short to ground circuit.
• If the short to ground could not be detected:
― Replace the BCM. (See BODY CONTROL MODULE (BCM) REMOVAL/INSTALLATION.)
No
Replace the climate control unit (A/C request signal always ON).
(See CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER].)
(See CLIMATE CONTROL UNIT INSTALLATION [MANUAL AIR CONDITIONER].)
7
Inspect the A/C relay.
(See RELAY INSPECTION [MZR-CD 2.2].)
Is the A/C relay normal?
Yes
Inspect and repair for short to ground circuit between A/C relay terminal E and PCM terminal 1BX.
No
Replace the A/C relay.
8
Verify test results.
• If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR-CD 2.2].)
• If the malfunction remains, inspect the related Service Information and perform repair or diagnosis.
― If the vehicle is repaired, troubleshooting completed.
― If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if later calibration is available.