Abstract: A roof-mounted air conditioning system has a built-in compressor compartment between the condensor and evaporator sections, the fans in the condensor section inducing the flow of air through the compressor compartment and into the condensor section through louvered vents in the partition wall between the compressor and condensor sections, and the air flowing from the compressor compartment is confined to flow directly across the condensor coils so as to satisfy the normal cooling requirements in the condensor section.