air conditioner problems 1994

I have a 1994 rodeo, v6, 4 wheel dr, approx. 133k miles...bought it used recently...here is the problem(s): turn on the fan, it blows...press the ac button and cold air comes out but it squells especially at an idol...belts have been changed and checked...ALSO, recently I turned on the fan and it wouldn't work at all...I slid the fresh air lever to recirculate and back and it start blowing and on top of that the squelling basically stopped...for the last couple of days it's flipped back and forth from all the above...any ideas? thank you

The squealing could be belts (which you check), fan clutch (????) or the bearing in the AC compressor yelling that they are old.

thank you...I will look into the compressor