Repairs or replaces 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, safety valves, and automatic gas valves. Conducts regular preventive maintenance inspections of refrigeration units and food service related equipment, isolated heating and ventilating units, including boilers, gas and electrically operated air-conditioning equipment, and makes necessary adjustments or repairs; services and repairs evaporative coolers.