Nissan Repair: compressor hissing, pressure release valve, expansion valve

Question
I have a 95 Sentra GLE, A/C stopped blowing cold. After a check discovered no refrigerant, I added a can. I heard hissing and discovered the leak coming from a fitting/nut on the bottom front side of the compressor. Is this something I can fix, or will I need a new compressor. I'm not going to start messing with it unless I know it's something I can do.

Answer
Barry,

The hissing is coming from the over pressure release valve.  You probably have another problem causing the over pressure like a stuck expansion valve.  If there is too much pressure the over pressure release valve will release pressure as not to blow a hose.  Have your system professionally checked and they can tell for sure.  Basically, the high pressure side will go nuts (over 300 PSI) and the low side will suck way down.  You will know you have a blockage and that is probably the expansion valve being stuck.