My 98 Frontier will cycle the AC compressor. Many hours of study and learned alot but not how to fix my air conditioner! I have the pressure switch jumpered out and it still will not run. I checked every circuit that I can find on the schematic and they all seem good. The only thing missing seems to be that it isnt getting a ground from the ecu. My book and any other schematic that I can find doesnt go any farther than that, or am I missing something obvious. Is it correct to say that if the pressure switch is jumpered out and all circuits are good that the compressor should engage weather or not the system is running the correct pressures. Also, the clutch does engage if power is supplied to the clutch. HELP!!!