How to make an Evaporative Air Cooler out of a Box Fan! Evap./swamp coolers are great for dry climates. step by step instructions will show you how to do it. can drop temperatures up to 30F. for added cooling use ice/cold water. can be solar powered. note: the fan can still be used like a regular fan even after the conversion. the cooling pad is very porous and has almost no effect on the fan motor or the volume of air that flows through the fan. Note: To see video of my latest box fan design, visit my youtube channel video page and look for Homemade Evaporative Cooler! - whole room Super Cooler! - up to 30F drop! - Easy DIY