AC Compressor Clutch Not Working on 1995 GMC Vandura 2500

I have recently replaced the ac compressor, now the clutch is not working. I have feel like I have tried everything, even some new connectors, what is going on and why will the compressor not kick on??

Asked by for the 1995 GMC Vandura 2500
need to replace high or low pressure cut off switch , or bypass them with wire.