Hector,

I just changed out my dash a/c compressor and it was also leaking out the back of the case at the shaft seal. I put on a new one and I'm going to rebuild the other for a spare. Mine also was low on oil, I drained about 3 0z and it should have had 14oz.

You would normally expect a hose or fitting leak, but the compressors themselves are probably the culprit on many a/c jobs.