AC Engaging

The air conditioning compressor on the wife's 2009 Civic LX coupe is engaging once in a while when no cooling mode or defrost mode is selected. I first noticed this as what I thought was en engine
stumble at highway speeds during a 6 hour interstate drive we were regularly making. After starting to pay better attention, I noticed it was happening at irregular intervals all the time. Maybe 2-3 times an hour that I could notice on highway drives. After a while, I started to get the feeling it was the AC compressor.
Finally, while idling near a curb with an outside temperature of 3F, I heard the famliiar click and condensor fan spinning up for about half a second. All this has been taking place in the regular heater mode with the floor vents selected.
Is there some function in the Civic that cycles the compressor once in a while just to keep it lubed up or something? Or do I need to start looking for wiring issues.
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Flatlander wrote:

according to the wiring diagram for a non-CNG, non-Hybrid, 2009 Civic:
the PCM turns on the compressor clutch relay, and the relay turns on the compressor clutch.
I don't see anything in operation theory about the PCM turning on the compressor unless you request it via the control panel selections.
GW
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wrote:

Thanks for checking that out. I suppose it could be a self test running every once in a while to make sure the clutch is still there, etc. Seems like something that would only run at power up, though.
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