I have a 2000 Civic EX where the heater control panel works intermittently with the engine running. So the blower control, rear defroster, etc turns on and off seemingly at its own will.

BUT with the ignition switch on and engine off, the heater control panel works as it should. I am truly stumped on this. Does anyone have any ideas as to what the problem may be? How is the heater panel wired differently between engine on and ignition switch on/engine off?

 

I found the problem. I did a power steering fluid flush a few days before the problem started to occur. In the process, I must have nicked the A/C wire harness and a piece of wiring from the harness became exposed.

Photo of culprit (exposed wire is near the yellow cap piece):


Wiring schematic: