REPLACE REBUILD THE FILTER-DRIER This is a requirement any time the system is opened to the atmosphere, regardless of whether or not you're converting to 134a. NOTE - Original Air offers replacement filter-driers for many applications, as well as customer rebuilding services if a filter-drier for your vehicle is not currently available.
DRAIN THE COMPRESSOR OIL AND REFILL WITH 134a COMPATIBLE OIL (PAG or Ester Oil) Most systems using the stock RV2 compressor use 11 oz. NOTE - Never use a flushing agent on the compressor. If the oil is too heavily contaminated, replace the compressor or have it rebuilt. Original Air offers replacement RV2 compressors for most Mopars, as well as customer rebuilding services as well as rotary compressor and a/c performance upgrade kits.
INSURE THAT THE SYSTEM IS CLEAN AND FREE OF CONTAMINANTS This is a good habit to get into, regardless of whether or not you're converting the system to 134a as it can insure against contaminating the rest of the system and/or loss of warranty and newly replaced parts. Depending on component condition, this may be a simple matter of blowing out with compressed air or liquid flushing with an air-conditioning liquid flushing agent. NOTE - All parts should be flushed individually, removed from the vehicle.
REPLACE OR RESTORE ALL RUBBER HOSES Replacement hoses should be made of barrier hose to prevent the 134a refrigerant from leaking through. NOTE - Original Air offers replacement hoses for many applications, as well as customer hose restorations services if a hose for your vehicle is not currently available.
REMOVE THE EPR VALVE FROM THE COMPRESSOR & INSTALL A THERMOSTAT. The EPR valve is located in the RV2 compressor's suction port (in the back of the compressor). It is designed to work exclusively with the old R12 refrigerant and cannot be adjusted. Once removed, the air-conditioning system will require something to let it know to cycle off/on, so a thermostat will need to be installed.
REPLACE OLD O-RINGS WITH 134a COMPATIBLE O-RINGS.
CORRECT CHARGE AMOUNT - The typical 134a charge of a factory R12 system is 70-80% of the original R12 charge amount. NOTE - Ignore the sight-glass. A properly charged 134a system will likely show bubbles in the sight-glass. If your sight-glass is clear with a 134a charge, the system is significantly overcharged.