my a/c clutch is not engaging

there should be a pressure switch so that it doesn't run when there's no freon , perhaps that is bad

Check clutch gap on compressor. I bought one for a previous car I owned and the gap was not even close. It would prevent the magnetic clutch from engagement. First thing is to make sure your are getting power to the compressor perhaps you already did that. Other thoughts are expansion valve can cause these types of issues another flow pinch point. Hoping it's just a gap adjustment issue and not another part needed such as valve or condenser being blocked up. Good Luck!