2000 Cavalier Air Conditioning question?

I have a 2000 cavalier that the airconditioner turns on in 3 of the 6 defroster/fan settings without pushing the a/c switch. I have changed out the entire heater/air cond. control panel and the instrument cluster without any effect. Has anyone else had this problem on a Cavalier or heard of it before. It works great, it just turns on in recirc and both defrost modes without me pressing the a/c switch --- BCM maybe? the in-line diode by the compressor? It's obviously picking up a ground from somewhere.........any ideas?