I don't have an issue with R134A. Usually when you do you have an installation issue. I converted hundreds. I can probably go out on a limb and say most vacuum pump are no efficient. Moisture and air are an enemy of an AC system. Just because the gauge reads 30" when you are pumping it down does not mean it works and I have never seen an air operated vacuum pump work properly. If you want me to go into again I will be happy to
