A/C temperature fluctuating?

Just purchased the vehicle listed above and as soon as I drove it off the lot the A/C temperature started fluctuating from ice cold to kind of cool. I took it in, and they put a new compressor in then I got it back and was still doing same thing, so I brought it back. Then they claimed to flush out the system 2x and recharge it. They did not see any fluctuation after driving for about 15 miles and car idling. I had it back for a week and am noticing it doing it again just not as frequent. I'm in AZ and the temps have gone from high 80's to mostly high 90's with a few days in the 100's it is noticeable on all days.