Just bought a 1996 silverado. A/C compressor had been replaced with a bypass pulley. I installed a new compressor, evaporator, condensor, orfice, dryer, & high pressure liquid line. Checked fuse in side of dash, and the relay fuse under the hood. Charged with 1 can of 134a and it wouldn't take the 2nd can. Started truck and turned on the A/C by pressing 'A/C' button on control panel. It does not light up and the unit does not start. Bypassed cycling switch and the unit will not cycle the clutch. Wiring harness is plugged in to the front top of the compressor & into the high pressure switch coming out of the 'Suction & return' line block on the back (top) of the compressor. Also pulled the control panel out of the dash to make sure everything was plugged in. Can't find a problem. Any suggestions?