A/C Compressor Won't Kick On

I am no way a/c knowledgeable, but I think MoparBrit has the idea. The ones I've done will take in enough freon for the compressor to start once they have been vacuumed down & have no leaks. You just have to hook up the can to the gauges & give it a little time. I never had to jump the low pressure switch to get freon to go in the system.