To reduce the fouling of heat exchangers, the plasma polymerized films have been applied to the heat transfer surfaces, and an effect of plasma polymerized film on fouling was investigated. Monomer and reactive gases were used as source for polymerization. Plasma polymerized films were deposited for pressure, power, and ratio of gases. The plasma polymer films served as functional layers of good wettability and high resistance to corrosion. Wettability of plasma polymerized film could be controlled by the change of the ratio of gas mixture. Hydrophilicity of plasma polymerized films on the heat exchanger in air conditioner can provide improvement in performance resulting from good water drainage, and hence a decrease of pressure drop. DC-plasma polymerized films improve resistance to corrosion which is contributing to deposit formation in heat exchangers. The difference in the build up of fouling deposits between bare substrate and plasma polymerized substrate was investigated by secondary electron microscopy (SEM). An effect of plasma polymerized film on fouling of heat exchangers was discussed in terms of surface properties such as wettability, surface chemical state.