Install services and repairs environmental-control systems in office buildings, and other commercial establishments, utilizing knowledge of refrigeration theory, pipefitting and structural layout, mounts compressor and condenser units on platform or floor, using hand tools, following blue prints or engineering specifications, fabricates, assembles and installs ductwork and chassis parts, using portable metalworking tools and welding equipment, and install evaporator unit in chassis or in air-duct system, using hand tools. Cuts and bends tubing to correct length and shape, using cutting and bending equipment and tools, cuts and threads pipe, using machine-threading or hand threading equipment, joins tubing or pipes to various refrigerating units by means of sleeves, couplings or unions and solders joints, using torch, forming complete circuit for refrigerant, installs expansion and discharge valves in circuit.