Just bought a 91 F350 custom with a flatbed. It needs work - some i can do, some i will leave to the professionals. My air was blowing nice and cold but when I would idle, the belt would start to squeal. Now the belt no longer squeals and i no longer have any cold air. Are there any older threads someone can direct me to that will help me with this problem?

 

Inspect the belt. Probably a good idea to replace it. See if the compressor clutch engages. If it doesn't engage then it could be a bad compressor/clutch, or the syatem could be low on charge.

 

Had the same thing happen a month or so back, when I hit ac it would squeal. I waited long enough and the clutch blew up which engaged the compressor and it locked up soon afterwards. That resulted in compressor change out in a local farm store parking lot. Might want to be proactive in getting it swapped out.