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

id0103d5803000

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 stuck engagement
•  A/C relay is stuck closed
•  Improper A/C compressor magnetic clutch clearance
•  Short to ground in wiring harness between A/C relay terminal E and PCM terminal 1I
•  A/C relay to magnetic clutch circuit short to battery power
•  Short to ground in wiring harness between climate control unit and PCM terminal 1AU

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION
1
Perform the KOEO or KOER self test.
(See KOEO/KOER SELF TEST [MZR 2.0 DISI].)
Are any DTCs displayed?
Yes
DTC is displayed:
•  Go to the applicable DTC inspection.
Communication error message is displayed:
•  Open circuit in wiring harness between main relay terminal B and PCM terminal 1AT
•  Open circuit in wiring harness between main relay terminal C and PCM terminals 1BE, 1BF
•  Main relay is stuck open.
•  Open or poor ground circuit (PCM terminals 1AZ, 1BB, 1BD, 1BG and 1BH)
•  Poor connection of vehicle body ground
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 magnetic clutch disengage?
Yes
Go to Step 5.
No
Go to the next step.
3
Switch the ignition to off.
Disconnect the magnetic clutch connector.
Start the engine and idle it.
Does the magnetic clutch disengage?
Yes
Inspect for short to power supply circuit between magnetic clutch terminal A and A/C relay terminal C.
Repair or replace the wiring harness for a possible short to power supply if necessary.
No
Go to the next step.
4
Verify the 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 the magnetic clutch for stuck.
(See MAGNETIC CLUTCH INSPECTION [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH INSPECTION [MANUAL AIR CONDITIONER].)
Replace the magnetic clutch if necessary.
(See MAGNETIC CLUTCH DISASSEMBLY/ASSEMBLY [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH DISASSEMBLY/ASSEMBLY [MANUAL AIR CONDITIONER].)
No
Adjust the magnetic clutch clearance.
(See MAGNETIC CLUTCH ADJUSTMENT [FULL-AUTO AIR CONDITIONER].)
(See MAGNETIC CLUTCH ADJUSTMENT [MANUAL AIR CONDITIONER].)
5
Access the PCM PID AC_REQ using the M-MDS.
(See ON-BOARD DIAGNOSTIC TEST [MZR 2.0 DISI].)
Monitor the PCM PID AC_REQ while turning on and off the air conditioner by switching the control panel.
Is the AC_REQ PID always ON?
Yes
Go to the next step.
No
Go to Step 7.
6
Inspect the refrigerant pressure switch.
(See REFRIGERANT PRESSURE SWITCH INSPECTION [FULL-AUTO AIR CONDITIONER].)
(See REFRIGERANT PRESSURE SWITCH INSPECTION [MANUAL AIR CONDITIONER].)
Is there any malfunction?
Yes
Replace the refrigerant pressure switch.
(See REFRIGERANT PRESSURE SWITCH REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
(See REFRIGERANT PRESSURE SWITCH REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
No
Inspect for short to ground in wiring harness between climate control unit terminal 1U (Full-auto air conditioner)/1L (Manual air conditioner) and PCM terminal 1AU.
•  If there is no malfunction:
―  Replace the climate control unit. (A/C request signal always ON)
7
Inspect the A/C relay.
(See RELAY INSPECTION.)
Is there any malfunction?
Yes
Replace the A/C relay.
No
Inspect for short to ground in wiring harness between A/C relay terminal E and PCM terminal 1I.
Repair or replace the wiring harness for a possible short to ground if necessary.
8
Verify the test results.
•  If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0 DISI].)
•  If a malfunction remains, inspect the related Service Information and perform the repair or diagnosis.
―  If the vehicle is repaired, troubleshooting is completed.
―  If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 2.0 DISI].)