Well, i have a 94 22re. I have had it for a couple months, and living in Texas ive used the A/C since i got it. never any issues and blowing cold. UNTIL it started getting over 90 degrees. when i start the truck and turn ac on it wont get cold, and when the compressor kicks on it screams. ive looked and saw that the compresor isnt spinning all the time. BUT once i drive it a little bit everything works perfect and cold. and great when it is cooler (in the morning). I have been told to replace the compressor, but also told i might just have to SHIM THE COMPRESSOR???

 

I was having a similar problem like that too on my 91 & it was the pulley on the compressor that was locking up from time to time causing it to squeal. It eventually froze up & I just changed the compressor.