[j cAT]

your system came with R12 . so someone did a conversion. if the wrong oil was added at some time this is what can happen. next the compressor valves are shot this also gives this type failure. orifice tube should be near the input of the filter dryer / out of the condenser ,but not too sure exactly on the c30.

ac tech should be up to speed on this though.

I am guessing on the R12 conversion but would be very surprised if its still in there. normally a conversion using the old compressor does not work as long unless the system was opened up and flushed out .