I've got all new or remanufactured A/c components for my 73 Charger. I emailed Classic Auto Air and they told me if I was running original system to take out the EPR valve on the compressor and add a thermostat. I talked to some veteran mechanics I know and they said using it just how it is shouldn't effect it using R-134a even with the EPR valve still in. I haven't contacted Vintage Auto Air but was going to ask their opinion. Has anyone here run R-134a w/ the RV-2 compressor and kept the EPR valve in and had luck?