The technician from Barrus Heating And Air was very helpful, honest and did everything he had to do. I was expecting much worse, but it turned out to be a minor problem. I have a two-zone house, and the upper zone wasn't working. A friend of mine said it could be a variety of things, but he didn't have the time to diagnose the problem, so I called Barrus. They did a pressure test, and didn't discover a leak. I'm guessing somebody stole the Freon out of the system. At one hundred dollars per pound, it wouldn't surprise me. So the technician from Barrus recharged the Freon a bit, did the pressure test again, and still didn't find a leak. So he purged the system and recharged it fully. Now it works fine.