NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY[LF, L3]

id0103b2803000

24

A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY.
DESCRIPTION
A/C compressor magnetic clutch does not disengage.
POSSIBLE CAUSE
•  Stuck engagement A/C compressor magnetic clutch
•  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.
Retrieve any continuous memory, KOEO and KOER DTCs using M-MDS.
Are there any DTCs displayed?
Yes
DTC is displayed:
Go to appropriate DTC inspection.
(See DTC TABLE[MTX, LF ATX (FS5A-EL)].)
(See DTC TABLE[LF ATX (FN4A-EL), L3 ATX].)
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 following:
•  The A/C relay is stuck closed.
•  Short to GND in wiring harness between A/C relay and PCM terminal 1I*1, 1AN*2.
If both items normal, go to the next step.
No
Inspect if circuit between the A/C relay and magnetic clutch shorts to battery power circuit.
•  If the circuit is normal, inspect for magnetic clutch stuck engagement or clearance.
3
Connect M-MDS to DLC-2.
Access AC_REQ PID.
Start engine and turn A/C switch on.
Read 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 GND may be present.
Does AC_REQ PID remain On?
Yes
Inspect for short to GND in wiring harness between refrigerant pressure switch and PCM terminal 1AU*1, 1AP*2.
No
Go to the next step.
4
Reconnect refrigerant pressure switch connector.
Read 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 GND may be present.
Does AC_REQ PID remain On?
Yes
Inspect the following:
•  Short to GND in wiring harness between the A/C switch and A/C amplifier
•  Short to GND in wiring harness between the A/C amplifier and refrigerant pressure switch
No
Inspect for stuck closed A/C switch.
5
Verify test results.
•  If normal, return to diagnostic index to service any additional symptoms.
•  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.

*1  :MTX, LF ATX (FS5A-EL)
*2  :LF ATX (FN4A-EL), L3 ATX