AC is altitude sensitive...?

[Matt Weiser]

I took a drive up into the mountains the other day and at a certain point, the AC started blowing warm. Coming back through the same point a few hours later (at around 4,000 feet altitude) all of a sudden the AC started working again. Nothing else different. The rest of the way down the mountain it was intermittent until finally it stayed cold after I was below about 2,000 feet.

What could cause this? Is there a valve or something that's pressure sensitive, maybe the thing that controls the flapper in the dash?

The system was just converted to 134a and has a brand new compressor.

 

[XLR8]

I don't know what your problem is, but I live at 5400' and my AC always works fine. Even when I used to take it up in the mountains - over 10,000' - the air always worked.