Abstract: A contoured A-coil heat exchanger is provided which enhances cooling capacity of the heat exchanger by increasing the volume rate of airflow therethrough. The two slabs of the A-coil each have discrete upper and lower sections, with the upper section of each slab having a greater number of rows of tubes than the lower section thereof, so that the lower section of each slab is narrower than the corresponding upper section. Therefore, the condensate collecting channel of a drain pan used with the heat exchanger can be made commensurately narrower because the channel need only be wide enough to accommodate the lower sections with fewer tube rows than the upper sections. The narrower channel allows the area of the drain pan central opening to be larger for a given size drain pan, thereby increasing the volume rate of airflow through the central opening and through the heat exchanger.