w126 300sel AC

[xaliscomex]

Own a 1988 w126 300sel and wondering if you can use r12 on a brand new oem AC compressor. My car is at the shop and the tech called me this evening to tell me that that when he charged the car with r12 it was not cooling all that well. Then he said something about charging it more and that the r12 shot out. He said he was going to try r134 tomorrow to see what happens. He also said that the new AC compressor has a stamp or label on the outside that states to use r134 only....Is he telling me the truth about the compressor maybe not being compatible with r12? Are the new compressors fitted with different hardware inside making it impossible to use r12? They also just installed the new OEM AC compressor...Please advise