Abstract: An air conditioning system for powered aircraft is provided wherein a refrigerant compressor is located immediately adjacent to the alternator at the right forward portion of a horizontally opposed aircraft engine. The compressor is mechanically driven indirectly from the main bulkhead/starter ring gear assembly through a twin sheaved pulley on the alternator. The air conditioning system also is provided with two sets of inlet ports for cooling air flow to a refrigerant condenser. One set of inlet ports accepts ram air when the aircraft is airborne. The second set of ports is closable and accepts air when an interior intake impeller is activated. The engine-compressor-alternator combination fits within an aerodynamic cowling having no greater frontal area than one required for the engine without the compressor.