Repair or replace defective parts in units and equipment and their controls, including thermostats, automatic switches, fan controls, log switches, damper motors, louvers, relays, filters, controls, belts, compressors, heat exchangers, high limit controls, pressure controls, and safety valves. • Inspect, repair, modify, and install HVAC equipment, including refrigeration and air conditioning compressors, receivers, condensers, chillers, water cooling towers, forced air converter units, pumps, automatic and hand valves, expansion valves, and capillary tubes.