Cooling fan

 A swamp cooler (more formally called an evaporative cooler) is essentially a large box-like frame containing a big fan and walled in by water-wetted pads, usually made of cedar shavings or cellulose. The fan whooshes the hot outside air through the dripping pads (which are continually soaked by a water pump), evaporates water molecules from the pads. The fan then blows the water-cooled air through the house and out a deliberate vent.
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