Abstract: An air conditioning apparatus and method for cooling enclosures containing electronic equipment. More particularly, one aspect of the present invention comprises a low cost passive heat removal system that utilizes a plurality of flat tubing or low profile extrusions. The flat tubing or low profile extrusions are arranged in parallel to create an air-to-air passive heat exchanger which may be incorporated into an air conditioning apparatus constructed in accordance with the present invention. The flat tubes or low profile extrusions offer a greater surface area and more efficient cooling than conventional folded fin designs having the same overall dimensions or volume. Moreover, the flat tubes or low profile extrusions may be manufactured with dimples, fins, or other surface enhancements with little additional labor or manufacturing steps. The air-to-air passive heat exchanger may be arranged in various configurations including cross flow, counterflow or concurrent flow.