airconditioner spraying gas out the back of compressor

my 97 discovery is spraying r134 gas out the back of some sort of relief valve on the back of the compressor. what will cause this to happen?

Thanks,

Ronnie

my first question is dose the a/c work. if it dose then lock for and obstruction in the lines. the gas is also a sourse for a leak that will have to be addressed. it could be the problem. obstructions like a faulty regulator or valve or control relay. hope it helps, gotta love a rover. duboff.