Roman works through a real-world mystery HVAC unit, diagnosing a cascade chilled water system step by step: from a water pump overload alarm and bearings that have seen better days, to a high-pressure trip caused by a stuck ice cube relay and a dirty condenser coil. Along the way, he covers refrigerant pressures, motor amp draw vs. nameplate ratings, voltage verification on foreign equipment, and a few improvised fixes that only a seasoned tech would think of.

Whether you’re an apprentice or a veteran, troubleshooting unfamiliar equipment is one of the most valuable skills you can develop — and watching Roman think out loud through each fault is a masterclass in systematic diagnosis.