Respond to dispatched service calls at customer sites to diagnose, troubleshoot, repair, and perform preventative maintenance on a wide range of commercial/industrial HVAC equipment, including but not limited to: Unitary and Packaged Systems — From small mini-splits to large rooftop/package units (up to 50+ tons); troubleshoot VFDs, controls, compressors; perform maintenance, repairs, and replacements. Chillers — Diagnose and repair compressor, motor, starter, and drive issues (including Wye-Delta, AFD/VFD, and solid-state starters); perform leak detection on low-pressure systems; conduct insulation resistance (Megger) testing on motors; execute full teardowns, rebuilds, and overhauls of compressors, oil systems, and starters.