Change the roof or change the A/C system? June 19, 2012   Subscribe Cooling the second story: Replace the roof or dual-zone the A/C?A lot of people want to use RV air conditioners for mobile applications because they don't want to cut a hole in the side of their trailer/truck.  They are not a great option. They are very expensive per BTU -- especially when you try to find one with a digital display. Dometic makes the original "BRISK" RV air conditioner which is digital. ***2016 models have a kit to change the thermostat to digital.  No customers that we know have tried this yet.  They have a sleeker looking one that is more expensive called the "Penguin" that's actually NOT as good for this application. So get the cheaper one, it's bigger on top which gives us more cooling area. If you still want a roof mount AC consider this: They are annoying to set up, because you are working over your head and up in a hole and you can't see what you are doing, so it's hard to put our FIN sensor into place correctly.