I suspect from the looks of it the freon was gone a long time ago. It has no belts on it so that's a good indicator that it quit working. However, if it's all intact I would try vacuuming the system and see if it will hold vacuum. From the age of it it would have had R12 in it. Usually if it has been converted to R134 it should have adapters for 134 hose connections. If (doubtful) it holds a vacuum without leaking down and you want to invest enough to try it, there are R12 substitutes available that do not require an oil change. I don't know what the R12 substitutes cost but R134 is about $15 per can now so you are looking at about $50 just to try it. Also you would need belts and you would need to verify that the clutch is working. Those old York compressors were good in their day but there's much better compressors available now and even complete new a/c systems available so there's probably not much value in that system.