Abstract: An air compressor includes an enclosed housing with a 12-volt electrical motor mounted to a bottom frame within said housing and a compressor pump located vertically above the motor within the housing and operably connected to the motor. A ventilation fan is mounted on the motor adjacent a ventilation panel in one side panel of the housing, to draw air into the housing. The top cover is spaced slightly above the upper edges of opposing side panels of the housing, to form a ventilation space at the upper end of the housing through which air may be circulated around the motor and pump and upwardly out of the housing. The compressor pump is mounted on a base plate which is pivotally mounted along one edge and has an adjustable length leg supporting the opposite edge. The adjustable length leg permits adjustment of the distance between the pump and motor so as to adjust the tension on a drive belt extending between pulleys on the pump and motor.