NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [MZR-CD (RF Turbo)]


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


STEP	INSPECTION	RESULTS	ACTION
1	Perform self-test function using WDS or equivalent. Turn the engine switch to the ON position. Retrieve any DTC. Is DTC displayed?	Yes	DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD (RF Turbo)].) Communication error message is displayed: Inspect for the following: • Open circuit between PCM control relay and PCM terminal 53 or 79 • Open circuit PCM control relay and PCM terminal 69 • PCM control relay stuck open • Open or poor GND circuit (PCM terminal 65, 85, 103 or 104) • Poor connection vehicle body GND
1		No	No DTC is displayed: Go to the applicable DTC inspection. (See DTC TABLE [MZR-CD (RF Turbo)].)
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 followings: • A/C relay is stuck closed • Short to GND circuit between A/C relay and PCM terminal 73 If both items are normal, go to the next step.
2		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	Start the engine and turn the A/C switch on. Measure the voltage at PCM terminal 84 while disconnecting the refrigerant pressure switch connector. Note • PCM terminal 84 voltage should read B+ when disconnecting connector. If PCM terminal 84 voltage reading remains below 1.0 V, short to GND circuit may be present. Is the voltage B+?	Yes	Inspect for short to GND circuit between the refrigerant pressure switch and PCM terminal 84.
3		No	Go to the next step.
4	Reconnect the refrigerant pressure switch connector. Measure the voltage at PCM terminal 84 while turning off the A/C switch. Note • PCM terminal 84 voltage should read B+ when turning A/C switch off. If PCM terminal 84 voltage reading remains below 1.0 V, short to GND circuit maybe present. Does voltage remain B+?	Yes	Inspect for the followings: • Short to GND circuit between A/C switch and A/C amplifier. • Short to GND circuit between A/C amplifier and refrigerant pressure switch.
4		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 the PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)