Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.

NO.24 A/C ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY TBR BP WITH TC] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	Connect WDS or equivalent to DLC-2. Turn ignition switch to ON. Retrieve any DTC. Is "PASSED" displayed?	Yes	No DTC displayed: Go to the next step.
1		No	DTC displayed: Go to appropriate DTC test.
2	Start engine and run it at idle. Turn A/C switch on. Remove A/C relay. Does A/C magnetic clutch disengage?	Yes	Inspect for following: A/C relay is stuck closed. Short to GND circuit between A/C relay and PCM terminal 2K If both items are okay, go to the next step.
2		No	Inspect if circuit between A/C relay and magnetic clutch is shorted to battery power circuit. If circuit is okay, inspect magnetic clutch stuck engagement or clearance.
3	Disconnect high-pressure switch connector. Start engine and turn A/C switch on. NOTE: A/C should not work when disconnecting connector. If A/C system remains working, short to GND circuit may be present. Does A/C remain working?	Yes	Inspect for short to GND circuit between high-pressure switch and PCM terminal 4F.
3		No	Go to the next step.
4	Reconnect high-pressure switch connector. Turn off A/C switch. NOTE: A/C should not work when disconnecting connector. If A/C remains working, short to GND circuit may be present. Does A/C remain working?	Yes	Inspect for short to GND circuit between high-pressure switch and A/C switch.
4		No	Inspect if A/C switch is stuck closed.
5	Verify test results. If okay, return to diagnostic index to service any additional symptoms. If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, replace PCM.