Abstract: An air conditioning unit for heating or cooling the cab of a tractor or other vehicle. A rectangular housing is mounted to the roof of the cab. It includes front, back and side walls which are upright and spanned by a horizontal cover. A central transverse shaft is rotatably mounted within the housing and extends between the housing side walls. It rotatably carries blade assemblies for central blowers and side blowers. The housing is divided into front and rear compartments by a solid interior transverse partition which isolates the two sets of blowers. A compressor is mounted within the housing and also has a transverse shaft. A common hydraulic motor drives both the central transverse shaft and the drive shaft of the compressor. The front compartment includes an inside coil and air inlets for directing fresh air and return air through the inside coil. The rear compartment includes an outside coil. The two coils are interconnected with a compressor in the manner conventional to a heat pump system.