When I was ordering my vintage air stuff the guy said the evaporator, compressor and condenser has to be designed for 134. As long as it all is, it's just as cold. How many cars AC systems in the last several years haven't been cold? I think in the early days of the switch they were just using 134 in the old style hardware. When I was at the AC shop getting my hoses crimped, that guy said they are talking about doing away with 134 in the next few years.