While everyone has good intention, everyone is just guessing what the problem is.
A/C systems should only be serviced by qualified personnel. They are very complicated systems and you need special tools. Yes, the refrigerant could have leaked out. In that case a UV dye has to be put in CORRECTLY and the leak has to be found and corrected. Do you have manifold gauges? Do you know how to handle refrigerant?? Do you have a vacuum pump?
The only thing I’d recommend you try is when the car is running, find a fat monkey wrench or broom stick handle and wack the compressor clutch (it’s the pulley where the belt drives the compressor). If the clutch engages, that means the electro magnet is worn out or out of spec. Either way has to go to a pro.
Don’t go in fiddling around with AC systems, leave it to the pros otherwise you can do more damage. There’s a lot more than just “tossing on a new compressor”.
15 years auto technician