chevy suburban AC problems

I am having a A/C problem on a 1996 chevy suburban. The A/C is not blowing cold air and compressor is not engaging. I First check pressure on low side which read zero. I charge the system with the ac on full and pressure is at 35 with hardly any of the can so I knew the compressor was not engaging. So I check the accumulator by passenger side and it gets voltage when I hit the AC button. so then I check the wire that leads to front of AC compressor by the pully and I dont see any volatage going to there with everything on. There is also a some wires going to the backside of the compressor but I did not check those yet. Any ideas on what to check to see if I can get the AC clutch to engage. - Thanks for any advice