A/C had stopped blowing cold the compressor not turning on?

Noticed my A/C had stopped blowing cold. The compressor wasn't coming on. Checked relay and changed low pressure switch near the low side valve. Ended up borrowing gauges and discovered no Freon. Ii ended up changing my Schrader values for both sides,put a vacuum and it held up.added proper amount of freon and still nothing cold,changed my coil and it started blowing cold, drove home about 2 miles and around the block the next day and all of a sudden i noticed it had stopped blowing cold again.im still holding freon so currently the compressor isnt coming on,checked my relay switch and its good,im going to get under and check the plug from the relay to make sure its getting power to the coil, belt is still there. not sure where to go once i do that however.