I too agree it sounds silly to have one that only works on 120VAC or 12VDC. Propane fridges have been around for quite along time now. Maybe like posted above the new ones want to have a regular house type fridge in them using a compressor.
With this in mind however it doesn't seem like an easy way to run off 12VDC without having a built-in INVERTER if the fridge has an compressor type motor. Maybe they use a DC Compressor motor when on 12VDC.
OP sounds like he has investigated it by going to the manuals and they only work on 120VAC and 12VDC??? who knows what they are using at this point. Heating the ammonia in the original RV fridge seems easy to do with a 120VAC heater element, 12VDC heater element, or propane burner... Why create something different?
I know there are some DORM type fridges on the market that work on 120VAC or Battery so maybe this is the same type of thing. Never have looked into how those work.
Roy Ken
