The present embodiments relate to an air distribution apparatus for distributing conditioned airflow from a roof mounted air conditioner to the inside of a vehicle, which includes an inlet port adapted to receive the conditioned airflow from the roof mounted air conditioner. An outlet port, which is disposed adjacent to each longitudinal end of the apparatus, delivers conditioned airflow to the vehicle. An internal supply duct is adapted to evenly split the conditioned airflow to the outlet ports.