Automotive Air Conditioning Information Forum

Hello everyone. I really need someone to help me, as I've been going crazy trying to solve this problem. The a/c in my 2005 civic LX likes to run on its own at random times. With the a/c switched off, and the blower set on any setting, it intermittently turns on and off, sometimes staying on for long periods of time, and sometimes rapidly turning on and off. During this time, the a/c indicator light remains off, regardless of whether or not the system is running. To be clear, the compressor clutch and the fan both run when this is occurring. Often it runs long enough to freeze over, resulting in no usable a/c.

I have replaced all associated relays, the PCM, the multiplex unit, and the hvac control panel, with no results. I am unable to find an apparent short to ground in the wiring that I can see.

Can someone PLEASE help me solve this problem? ANY input is appreciated. If there is anything else in the system (pressure switch, temp sensor, etc) that is capable of turning on the compressor and fans, let me know. I really am sick of this.

I've attached the diagram for reference.

We had a similar issue last month with our 2005 Yukon. Blower motor would sometimes stay on even after key was removed. Sometimes blower motor would not run at all, so no AC. Mechanic replaced both the blower fan (which had some physical resistance) and the blower resistor, and that fixed it.

Unfortunately, I do not believe this has any relation to the blower motor. Our blower motor operates exactly as it should, and is controlled properly by the HVAC controls. Our AC condenser clutch and evaporator fans engage when they shouldn't, regardless of whether or not the blower is on or not.