Abstract: A self-contained air conditioner unit comprises an enclosure including a first and second intake apertures positioned to communicate with outside ambient air and first, second, and third outlet apertures positioned to communicate with a habitable space in which the air conditioner is placed. A water reservoir is disposed at the bottom of the enclosure. A two-section heat exchanger is disposed in the cabinet over the water reservoir, each section comprising a plurality of vertically disposed, alternating wet air channels and dry air channels defined by substantially parallel opposing heat-transfer partitions. The first-section dry-air channels communicate with a pre-mixing chamber at intake ends thereof and an air-distributing chamber at outlet ends thereof. Each first-section wet channel communicates with the distributing chamber at intake ends thereof and the second outlet aperture at outlet ends thereof.