Nissens' evaporators have been designed and manufactured with optimum heat exchange in mind. The hot air passes the evaporator's cooling fins, and the cooling gas in the evaporator absorbs the heat. At the same time, the air humidity condenses on the surface of the evaporator, and the water is gathered and led away along with dust, pollen, etc. As the evaporator is exposed to both temperature variations, high pressure, and moisture, it is important that design and manufacturing take these factors into account.