Is there a 'right' way and a 'wrong' way to convert from R12 to R134? I had an 82 converted and it never really blew cold air. At the time, I didn't know enough to know what the shop was doing. I know a little more now, at least enough to ask the question. I'm converting an '81 245 from R12 to R134 (or rather having it done). I'm now realizing that these days, sometimes you need to be able to tell the mechanic what to do.