AC was working fine yesterday, but today it started blowing ONLY hot air, regarless of the temperature wheel setting. The previous owner had the entire a/c system rebuilt, so I really wonder what's going on. Thanks for any help!

When chasing down my car's problems I found that the compressor did not engage which was a low freon condition. When that was corrected I sometimes would get hot air sometimes cold air so I replaced the internals of the mono heater valve and all is now well. There are threads here that relate to diagnosing air problems.

Problem is, when I turn on the AC, I can hear the compresser running, but it still spits out VERY hot air. Supposedly there is something behind the glovebox that disintegrates. I'll take a look.

Correct. The part is a foam tube which draws air past the thirmistor. If you check out this thread it will speak about it...

http://www.peachparts.com/shopforum/diesel-discussion/17031-82-300td-c-problem.html

Good luck.

Check my previous post titled "Haven't figured out the A/C problem". Lots of good info there which helped me figure out my problem. Latest reply to this post was on 6/10.