r134a or freon

It is best to replace txv to match refrigerant, but r-12 and 134 are pretty close as it will probably work ok (some are adjustable). I prefer the epr valve over the t-stat as it derates a/c instead of cycling compressor, but either will do. If you put a low pressure switch on the reciever than it is more of a loss of charge switch than a low pressure switch, I prefer to install a low pressure switch on suction line, especialy if using a t-stat instead of an epr valve.R-12 condensers are to small for 134 and will cause a high head pressure, this will not cause a problem but if you are replacing it anyway, maybe they offer a larger one. 134 charge is approx. 80% of r-12 charge, but is best checked to get best operation, especialy if changing componants.


Good luck and keep cool!