94 degrees today and the A/C is fluctuating between cold and hot moist air. I had my friend check it out around a week ago and it was low on R134A so we topped it up. Worked great for about a week then started doing the same thing again.
Here is what it's doing-for the first 20 minutes it blows nice and cold, as soon as I stop at a light (engine drops to idle) the A/C cuts out and starts blowing warm. It will not blow cold or even cool at idle. It was also cutting in and out on the highway, I shut it off for a few minutes and it would blow cold again for 10 minutes.
Tonight on the way home from my son's baseball game the temperature had dropped into the 70's and it blew cold the whole way home (40 miles)
WTF? Any ideas? Suggestions?
Thanks in advance.

 

bump, going to dealer this morning

 

My initial thought is, there's a reason your A/C system was low on R134A. You most likely lost some R134A to a small leak in the systems, in which case you may have already lost the additional R134A you just top it off with. A system with low freon/R134A will sometimes produce sporatic cool air depending on how much pressure the compressor is able to produce. The best way to find a leak is to put some A/C dye into the A/C system, run the A/C, and use a black light see if you can locate any dye leaking out.

Another thought, do you think there's any chance you/your friend may have over-charged the R134A?? Over-charging the A/C system can cause the evaporator the freeze up, which limits its ability to produce cool air.