David, As per the diagram, The voltage comes thru #10 fuse the goes thru the mode switch then goes thru a low pressure and some cars may also have a high pressure switch. or vice versa, If the fans are coming on, then that would mean the voltage is making it thru the switches and to The Fan Fix. Then the compressor isn't grounded good or it's bad. I'm not the greatest air man, but that's the diagram. It's pretty straight forward. John http://www.specialtauto.com/