A/C compressor had quit working. All fuses are good. I disconnected the low pressure switch wiring harness and did the jumper wire hook up, compressor did not come on, but when I ran a ground to one of the wiring harness terminals, the compressor came on and continued running even when I turned off the A/C. Naturally I unhooked the ground but what would cause this, any ideas? The A/C is ice cold when it runs.