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

BME010300103262

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 between A/C switch and PCM
• Short to GND circuit between A/C relay and PCM
• A/C relay to magnetic clutch circuit shorted to battery power

Diagnostic procedure

STEP

INSPECTION

RESULTS

ACTION

1
Connect the WDS or equivalent to the DLC-2.
Retrieve any continuous memory, KOEO and KOER DTCs.
Are there any DTCs displayed?
Yes

DTC is displayed:

Go to the applicable DTC inspection.
No

No DTC is displayed:

Go to the next step.
2
Start the engine and run it at idle.
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 circuit between A/C relay and PCM terminal 4O.
If both items normal, go to the next step.
No
Inspect if circuit between the A/C relay and the magnetic clutch shorts to battery power circuit.
If circuit is normal, inspect the magnetic clutch stuck engagement or clearance.
3
Connect the WDS or equivalent to the DLC-2.
Access AC_REQ PID.
Start the engine and turn the A/C switch on.
Read AC_REQ PID while disconnecting the refrigerant pressure switch connector.
Note
• AC_REQ PID should read OFF when disconnecting the connector. If AC_REQ PID reading remains ON, short to GND circuit may be present.
Does AC_REQ PID reading remain ON?
Yes
Inspect for short to GND circuit between the refrigerant pressure switch and PCM terminal 1AC.
No
Go to the next step.
4
Reconnect the refrigerant pressure switch connector.
Read AC_REQ PID while turning off the A/C switch.
Note
• AC_REQ PID should read OFF when turning the A/C switch off. If AC_REQ PID reading remains ON, short to GND circuit may be present.
Does AC_REQ PID reading remain ON?
Yes
Inspect the following:
• Short to GND circuit between A/C switch and A/C amplifier
• Short to GND circuit between 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, replace PCM.