This is a non-automotive question, and in no way related to the inline engine focus of this website, but to slake your thirst for knowledge let me elucidate you:
A "swamp" cooler is the nickname for an evaporative cooler system, common in the Southwest. It is not refrigerant based air conditioning, but uses a system of wetted pads (usually aspen fiber excelsior -- or newer synthetics) thru which air is drawn into a ducting system. The unit typically consists of a large tin box, say 4' cubed. The floor pan is waterproof and in it water collects and is pumped up thru a "Spider" to drip down into the pads on 4 or 3 sides, held in by tin louvered panels. Also at the bottom of the floor pan there is a small water pump that sends the water that drips off the pads into the pan back up to the spider. In the center of the box is a large squirrel cage type fan, powered by a 1/4 or 1/2 HP electric motor. The fan draws hot outside air thru the wetted pads and down into the house's ventilation system -- usually the same ducting used for heating in the winter. The water is fed by a float valve into the pan if it goes below a level.
It works best in areas where there is a constant low relative humidity, EG Arizona, NM, Texas -- it works less efficiently when the humidity rises. The advantage is, it's much cheaper to run than air conditioning, with fewer moving parts. They do work phenomenally well on a 100* day in Tucson, and can drop the interior temp down to 60 or 70*. Personally, I prefer the fresh scent of new aspen pads over the synthetic pads [which have no smell] but the latter don't go bad and require fewer changes during the season. Another disadvantage is metal parts stored in swamp-cooled warehouses can corrode if unprotected. A company called Dial Industries (?) in Phoenix sells a lot of units in this area. I don't know if they have a website.