A/C problems...

I'm new here so go easy on me.

I have a 2000 Xterrible that I started having A/C problem with back during the summer. It blows air, just not cold...not even cool. When it stopped blowing cold air, it started hissing and "groaning" every 20 seconds or so. Since then, I have taken it to a local shop 6 times during which time they have replaced the evaporator and the expansion valve twice and they have put countless amounts of refrigerant in. It is currently at the show now where they are doing more diagnostics and they said that the high side is high and the low side is high also. They said that the freon is not cooling and this could be due to a (fan clutch?) not pulling a fan. If this fixes it, I will let everyone know, but in the meantime...has anyone else out there had problems anything similiar to this. Thanks in advance.

I have a 2000 xterra with same ac issues. My X has been GREAT, except for the AC. I had to have something called the control thermostat replaced at 30000 miles, good thing it was still under warrenty. Recently at 57,000 miles the ac started blowing hot air. I'm familiar with the hissing sound you speak of as well. I added a can of freon after checking my high and low side pressure and that fixed the problem for about 10 days. I noticed that my high pressure line which runs from the compressor (metal hose that turns into a rubber hose) was covered with an oily residue. Turns out my high pressure line is leaking somewhere in this area. I added more freon this time with 2 ounces of stop leak. I'm on day 7, so far, so good. Sounds like you might have some other problems, just thought I would share my AC issues.