It can be pretty expensive (relatively) to get one operating correctly. You might get it to blow cold for $40-50 by just filling it full of auto part store refrigerant and oil but that isn't a very good way of going about things. You really need to have the system checked out for leaks and make sure your POA is working properly. Compressors can run $175- 500 alone. Is all of your electrical wiring in place and hooked up on the evaporator box? How about the Compressor hard lines? Are they all connected and in place? You will probably need a new drier no matter what if the system has be inoperable for a while.