greenman is right on the money here. I've fiddled with my AC on my old car and it was a hassle. I ended up blowing more money on tools and wasting so much time. Would've been cheaper to go to a shop. Granted the problem with your G6 is probably not as severe it's still a tricky system.
You can at least make sure the AC is clicking on, When you turn it on do you hear the compressor click on? If so then it could be a problem with the little doors and such in the dash itself. Not something directly related to the AC system... Although a pressure problem could still let it kick on but not function correctly