Its likely the air gap is too small , between the pulley and the plate in front of the
compressor that turn when its normally on , causing it to rub and create heat .
there are shims that move it further away , but if its gotten hot , its ruined .

Are you sure its not wired to come on, even with no freon? thatll burn it up! also if theres no oil in the system! your ac has to have oil. someone may have wired the low side switch to come on anytime you turn the defroster on or air. when the air isnt engaged the coaster bearings are all that spins. i think the air is on for some reason, is the clutch assembly turning when the car is running? ( the outside of the pulley ) it shouldnt

Probably a seized idler pulley, not the compressor.

You've got two problems which need to be attended to. One a pulley (probably the idler) is frozen caused the friction waer and noise. Second your compressor should not be running unless you turn it on. Without freon, which is a liquid on the low side, the comprssor oil isn't moving over all of the internal parts, thus they may be contribting to the noise, heat and wear. Fist get the electrical fixed, add freon and then the pulley - BEFORE you use it.

oops