Combines R 12 TO 134A

The old rule of thumb for automotive conversions was 80%, but this does not often work out for ag use. I have found that you start with about a 50% charge and slowly add 134a untill vent temp stops dropping. More will actually lower cooling capacity and raise high side pressure excessivly. No way would I bypass the low side switch. It is the only thing that keeps you from burning up the compressor if refrigerant is low or lost. In most cases cold start kick out is less of a problem with 134a. If you need to bypass the low press switch,I would bet the system is undercharged or has a bad TX valve.

we go by case's reccomendations - install the new high psi switch (400 psi vs 300 for the r12 switch),drier, fittings, and change the oil in the compressor(or replace compressor if it was leaking at fron seal). 4.25 lbs in 1400andearly 1600 w_york compressors, 4.75 lbs in 1600 w_sanden compressors. The conversions work good for the most part, except in really HOT days (95+) the high side will kick off the system if the guy doesn't keep the condenser and radiator clean. They're a little more touchy that way.