Thanks for the info cadillackid and I think your correct. I also found another interesting thing. I have 3 units interior units, the rear and middle are apart of one system. The front unit is the second system. For some reason when I turn the front unit, both the compressors engage and when I turn on the middle or rear unit, neither compressors engage. I think someone tied the signal to turn on both compressors to the front switch. If I unhook the compressor on the right, the front unit (the working one) stops blowing cold so that compressor is working. I may need to buy a set of gauges and check the pressure on the left side and see if is low or a bad compressor, which I'm thinking a bad compressor since that side has the HP, LP switch inline with the compressor signal. Also need to figure out why the units are tied together. A wire diagram would be really helpfull right now.