Freon

you should have it done by a professional , it leaked out and the stuff you put in will also leak out , and you';ll be mixing it with the residual air that's in the system , the parts of an A/C unit are mated to work together

None !! They use 134 A as a refrigerant in my world

Needs to be leak detected if its empty and fixed, may just need an o'ring, other-wise a small can, you can add more later, if that leaks out then you did not loose more to the atmosphere.