I dont know, my boss usually does all the a/c work. Oh one other thing that is used for testing, he will put the system under vacum and it it holds, then its good, if not he will fill it with compressed air and listen for leaks. You really need the gauges and fittings to do it though.

You can always try jumping the compressor to kick it on and see if the a/c blows cold again, if it doesnt you have no freon left. If it does, its either low or something is not letting the compressor kick on. I would have a trusted tech look at it.