Re-Charging AC Systems with R134a, Uncategorized

Converting a Mopar to R134a when the EPR is Missing

Upgrading your vehicle’s cooling system from the old R12 refrigerant can present a host of challenges. Here’s an issue we’re often asked about by Mopar owners.

I have converted my 68 Charger to R134a using a rotary compressor. Sometimes my system stops cooling and I lose air flow from the vents. What is causing this and how can I fix it?

It sounds like your evaporator is freezing up, which is likely due to removal of the EPR (evaporator pressure regulator) during the installation of the rotary compressor. This valve was installed in the stock RV2 compressor of most Mopar factory vehicles from this era. It was designed to regulate system pressures in order to prevent the evaporator from freezing up. When installing a different compressor, or when converting a stock system to R134a, the EPR valve is removed. Once removed, however, there’s nothing left to prevent the evaporator from freezing up.

Our rotary compressor conversion kits solve this problem with an electrical thermostat. The thermostat cycles the compressor clutch off when temperatures get too low, and back on once they get warm enough. For more information, download our Mopar thermostat installation instructions.

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *