The newer units are using R410a, which has been out for several years. I believe Dometic started using it in their marine units around 2007 or so. There were grumblings about it not cooling as well as R22, but the main difference is in the amount of gas used in the charges, usually in oz. The average use is not going to know the difference. Charging with it is a lot harder than with R-22 because of the extremely high pressures it runs at and it has to be charged either by weight or by super heat because ambient temperature really affects the high side pressures and a few degrees change can send the high side pressures all over the map.I've heard that a replacement is coming for it, but I don't have any specifics, so it looks like we will be living with this one for a while. You can't just charge it and get it close with gauges like you could R-22.
It's like when R-134a replaced R-12 in refrigeration. Nobody really noticed a big difference. I haven't noticed a difference in discharge air temps between the two. If you replace the AC in a stick & brick you are going to get a unit charged with R410a, trade name, Puron.
