Performs journeyman level installation, maintenance, service, and repair to heating, ventilating, air conditioning, and refrigerating equipment, including window and package units, freezers, water coolers, cooling towers, pneumatic systems controls, remote controls, pumps, compressors, condensers, and related parts and assemblies. Under general supervision, performs journeyman level installation, repair, service, and maintenance to heating, air conditioning, refrigerating, and ventilating equipment in County correctional facilities and leads or instructs lesser skilled workers and inmates.