Troubleshoots, maintains, inspects, modifies and repairs heating, ventilation systems, air conditioning and refrigeration systems and equipment including DX and hydronic systems and components, screw, reciprocating and absorption chillers, cooling towers, fans and fan motors, pumps and pump motors, electric controls and associated safety, over current and other equipment protection devices. Under general supervision, perform master journey-level work in the repair, maintenance, service, modification, troubleshooting, inspection and monitoring of the operation of heating, ventilating, air conditioning and refrigeration equipment and associated plumbing, electrical, mechanical, BAS (Building Automated System) and controls systems.