uneasy_rider

I have a project 89 S10 pickup that I am slowly working the bugs out of and need a little help on my A/C system. First off, the system is fully charged, the low pressure switch works, but I am getting no voltage to the coil on the compressor. I have read and been told that the issue could be the high pressure switch, but I am not for certain that it is used on this system or not, reason being: there is no wire hooked up to the switch, and I have looked at multiple trucks in a salvage yard that have no wire hooked up to it. I believe I have it narrowed down to either that or the a/c compressor control relay. BTW, this was a truck that I did a body swap from a 84 chassis/drivetrain to a 89 chassis/drivetrain, so wiring has been a small issue. Thanks for any help.