I have a Dodge Avco with two roof airs and they cool me really well. I have a Flxible bus conversion that has two roof airs and they keep the bus cool unless it is a real hot 100 degree day it could use one more. I have a GMC RTS bus that is being converted and I am going to use basement AC type system and want to freeze myself out of it . The bus has coach air that freezes me out of there but when stopped i don't want to run the main engine so I am going with a central basement system and there is enough room under the bus to get it installed. Basement type system is much nicer looking than roof air systems.