Could be due to a multitude of reasons. Without knowing more information or doing a AC test it's hard to tell. Likely it is either you are low on freon (for whatever reason) or faulty compressor. Could also be the condenser (less likely) Need to do a proper A/C test to know for sure. Good luck.

It could be from low refrigerant (a leak), either in a hose or the evap core, or perhaps a problem with the blend doors. Have it properly assessed. If you inject refrigerant when the problem is the blend doors, you might blow the system. (That mistake would cost you thousands). Take it to someone who knows what they're doing. That is, they won't do anything until they do a UV dye test, and ask you to drive it around for a bit.