A friend of mine has a salvage yard and has used a/c compressors for air supply on his trucks and forklifts for years but he uses the square York (usually found on old Fords) or Chrysler "V" type since both has it's own oil supply. I don't think the round rotary type would hold up long since it's lube is in the freon. He uses a large fuel filter on the suction side to keep the grit out.

Evan