many parts of the system will not work if the charge is not at least close. I'd go to an auto parts store and pick up a set of gauges. unless you already know, I'd take a picture of the a/c lines and post it here so we can tell if you have 12 or 134 in the system. after you get pressures, post them here too and we'll tell if it's low/empty/fine, and we can go from there.
another place for gauges is a pawn shop, but it's unlikely you'd get 134 adapters with them. (hopefully you don't need adapters!!!)