The evaporator, also sometimes referred to as the evaporator core, is one heat exchangers in a mobile A/C system. Evaporators are usually made of aluminum. They look like, and in fact are, similar to radiators, only thicker and smaller in overall size. Like radiators, evaporators consist of a series of internal tubes or “flow paths” with fins attached to them. Air can pass freely through the fins, just like a radiator. But unlike a radiator, where the internal tubes carry moving engine coolant, the passages in the evaporator carry moving refrigerant.