A method of transferring heat is accomplished by providing a heat exchanger unit that is at least partially air cooled. The heat exchanger unit has an evaporator, condenser, compressor and a fan for forcing air over an exteriorly located heat exchange surface of the condenser. A fiberglass filter element is positioned adjacent to the heat exchange surface of the condenser for capturing at least one of grease, debris and other contaminants that are not entrained within any liquid cooling fluid that would otherwise contact the heat exchange surface. The filter element is allowed to capture the at least one of grease, debris and other contaminants prior to contact with the heat exchange surface of the condenser.