Abstract: An enclosure for a vehicle air conditioning unit, the enclosure comprising a housing having an internal chamber, the internal chamber having a firewall positioned to define a first subchamber and a second subchamber, wherein the first subchamber is positioned proximate to a wall of the housing configured to be opposite a vehicle wall when the enclosure is mounted to a vehicle and the second subchamber is configured to be proximate to a vehicle wall when mounted to a vehicle and to receive an air conditioning unit; and a first set of one or more exhaust louver on a periphery of the first subchamber and a second set of one or more intake louver on a periphery of the second subchamber, the first and second sets of louvers allowing for air flow into and out of the enclosure. Air conditioning unit assemblies and vehicles including the enclosure are also disclosed, as are methods of reducing or preventing leaking of environmental water into an air conditioning unit mounted on a vehicle, using the enclosure.