X5 AC strange behavior

[sjennings]

My 2004 X5 AC is acting strange. Blowing cold air it "puffs" meaning that when turned on, it starts blowing cold air but works intermittently. It runs 30 sec. then stops then starts then stops.... It seems to happen more when stressed meaning very hot outside, but even if I change the settings such as put it on Max, it still stops and starts. If I put it on the lowest fan level it seems to run a little longer. There are times when the AC works fine for long periods of time. I called a Bimmerworks shop close by (Elsmere, DE) and the mechanic said that he has only seen this happen with one other X5 and he ran diagnostics but couldn't find the problem.

I am asking for advice since I had a "runs rough in cold weather " problem, took it to the dealership, and then spent $600 of my money replacing ALL the coils and I still have the same problem. So the dealer seems to have mechanics who just run diagnostics and replace the "light bulbs".

Has anyone seen the same AC problem? Recommendations?