This is for homes w/central air. The condenser part is located outdoors. PIC The whole outside of the unit is composed of small metal fins to cool down the condensor. Lowes sells several all-purpose cleaners. i just spray and rinse. They also sell 20% HCL acid solution to clean metal. The fins are metal. i just pour it along the outside. the condenser hasnt been cleaned since the house was built (13years). so all purpose cleaner, or acid solution?