回複：修過空調的大哥請進

If you want to make it work, I would recommend you to do the followings:
1) If your system is empty and has not been opened, charge one lb R134a with UV dye. Let AC run for a while.
2) Use a UV detector to find out the trace of dye leaked (in dark night). This step is to know where the leaking takes place.
3) Fix the leak. If it is from compressor, buy a new or rebuilt compressor (about $150 for rebuilt for most cars).
4) Replace O-rings in accessible connections due to aging of old ones (most likely it will leak again from those old o-rings).
5) If compressor is replaced, it's recommended to flush the system to remove contaminants (have a shop do it for you, about $50).
6) Receiver-drier must be replaced, but don't open it until just minutes before vacuum the system. Once installed, vacuum the system right away.
7) Sit your car over night and test if vacuum stays. If vacuum is lost, it means still leaking. Fix the leak. Minimize the system open time to save drier.
8) if no leak, charge up to full level. You will need the adapters (a pair) to be affixed to existing ports before charge. The adapters are about $10/pair from any parts store.
9) Above is minimum to make an AC work. For best result, replace entire o-rings, and replace expansion valve too.
10) For most cars, the cost including a rebuilt compressor is about $300-400.

If you have further questions, you can qqh me. Good luck.