Condensing units move refrigerant within a central air conditioning system to collect and release heat for regulating air temperatures inside homes, offices, and commercial and industrial buildings. They require connection to an indoor air handler or fan, which delivers the conditioned air into a building. Also called AC condensers, these outdoor units have a weather-resistant, heavy-gauge steel cabinet that houses and protects the compressor, condenser fan, condenser coils, and other interior components. Their condenser coil is made of copper tubing with aluminum fins for excellent heat transfer. They use chlorine-free R-410A refrigerant. Units with a heat pump provide cooling and heating for year-round use.