PETE
Guest
I have depressurized my system down to almost zero and installed R134 fittings. I then added 8oz of PEG oil along with about 2.5 cans of R134 until the return hose is cold. I have done this to two of my trucks and three tractors with no problems. As long as you do not let any air in the system you should be alright. Air contains moisture that will freeze in your system, the reason you pull a vacuum on the system is to "boil off" the water in the system.