Carrier Packaged AC - 3 Ton The 50TCM units are single side discharge rooftop cooling units utilizing electric heat as an option. Units are prewired, and pre-charged with R-410A refrigerant, and tested at the factory. These units can be placed on the side of a building or on a roof without roof curbs. Each unit is designed to occupy a minimal space, with piping and drain connections readily accessible. Carrier�s Package Rooftop Unit software makes selecting and optimizing the 50TCM easy.