My A/C was cycling on and off, about every 8 seconds. Not really cooling off the car on 88 degree days. My mechanic pal says it justs needs more R-134. So we hook up a can, with the A/C running on full blast, and it seems to fill normally. So I take it for a drive, and now it doesn't work at all!!! The compressor makes a double-clunk noise every few seconds; no cool air. Well, I get it home and figure I'll just make an appointment with the dealer. Then I get the idea to just let the car cool down a few hours, and try it again. To hedge my bet, I disconnect the battery to reset everything. Voila, 5 hours later it's working fine. What gives??