1998 Honda Accord Squeels

Ive had a problem for the last couple years. When I use the A/C, defrost or rear defrost my car makes a squeeling sound. If I am travelling at a constant speed it only squeels ever so often and momentarily and I feel a little tug. But if I am in stop and go traffic it squeels loud and for a long time until I rev up the engine. The problem began after AI had the AC charged (i think they may have overcharged it causing strain on the compressor bearings. I have been told that it was the belt which I replaced and was not the problem. Any ideas. Tension in flywheel? Bearings in compressor? What can I do to fix the problem?