There is no question that the number one thing all of us could use, in the
world of autos, is a reliable and reasonably priced mechanic and/or repair
shop.
Sorry for your experience. I am even more sorry that it happened at
Firestone, since in my community, Firestone is probably THE most reputable
and well respected repair place in the area. They have helped me with a lot
of things I can't do myself. If they knew where this place of yours was,
the people at Firestone here would make trouble to the national
headquarters, because they realize that all Firestone's are tarnished with a
bad experience at one.
As I said - the A/C charge kit is fairly inexpensive and fairly easy to do.
Try it, and if you are unsure, go to Autozone or someplace like it where
they can tell you exactly what to do on your car. If it works, you have
cold A/C, and the satisfaction of having done it yourself.
If it only works for a while, then gets "un-cold" again, then you know you
have a leak. Then ask friends and what have you for recommendations on a
reputable shop who can do a relatively inexpensive dye test that will
quickly tell them (and you, when they show you) where the leak actually is.
My first guess would be a hose - still not the cheapest part in the world
(A/C parts never are), but a whole lot better than a compressor or
condenser.
Hope this helps.
Tom Wenndt