Heat Pump Service Fundamentals

Service air-source heat pumps with real understanding, not guesswork: O vs B reversing-valve wiring, demand and time/temperature defrost boards, defrost termination sensors, auxiliary vs emergency heat strategies, balance point, and why you never verify charge in heating mode the way you would in cooling. Combines the heat pump service guide with HVAC fundamentals, controls, and refrigerant recovery so a technician can swap parts and set up defrost without breaking the heat cycle.