R134a can accomplish what like a little below 200 psi? If at all possible use dry nitrogen and fill to 150 psi then wait to determine if it leaks. Really don't use air and definitely Really don't use oxygen Until you want explosions. The Equipment Professionals is often a source http://remingtonhifbw.arwebo.com/19356682/detailed-notes-on-ductless-heating-and-air