Performs advanced troubleshooting, repair, installation, and maintenance of commercial HVAC equipment and systems, including air handlers, rooftop units, heat pumps, split systems, chillers, boilers, pumps, cooling towers, exhaust systems, refrigeration equipment, and associated mechanical components. Independently diagnoses and repairs complex electrical, electronic, pneumatic, and digital control systems, using meters, gauges, diagnostic equipment, schematics, wiring diagrams, and manufacturer documentation to identify and correct system deficiencies.