What is an Air-cooled aftercooler or why are they important, get all the details in this article? A compressed air aftercooler is usually custom-designed. An air cooler is a mechanism of heat exchanging that is designed to pull out the heat-of-compression from a compressed air stream. It also conditions the air (like maintain the temperature blowing out heat and keep the room normal or cool); that’s why it is used in air-operated equipment.