[Jim Sims]

N2 refrigeration regulators, attachment hoses (with fittings to attach to R-12 type schraeder valves), and small (40 cu ft.) compressed nitrogen gas bottles are available new on E-bay. Sears also sells said regulators and hoses. Bottles may be obtained or filled at your local welding supplies vendor or compressed gas source. One has to obtain or fabricate adapters to attach to the R-134a systems. Nitrogen is used for pressure leak checking for two reasons: It is dry and therefore doesn't introduce water into the system. It is also inert and lacks oxygen as opposed to air which at the high test pressures required (~300 psi) can become explosive especially in the presence of fuel (refrigeration oil). Get training with compressed gases before working with this leak checking method. As always, wear full goggles or safety glasses with side shields.