[svxistentialist]

Adam

Check that you have not built up a burnt rubber "glaze" on the AC pulley that would be promoting slippage.

If a worn or loose bearing was at fault, you would feel this as movement or rocking in the pulley when the belt is off.

It's also possible you have an aircon compressor fault. Maybe it is too difficult to turn because of a seized bearing? Find an aircon guy to look at it, see if the torque needed to turn the pulley is normal.

Joe