During the defrost cycle, which mode does the system switch to?

During the defrost cycle of a heat pump system, the unit typically switches to cooling mode. This may seem counterintuitive, but the purpose of the defrost cycle is to remove frost buildup on the outdoor coil, which can impede the heat pump's efficiency. In cooling mode, the heat pump reverses the flow of refrigerant. This reversal allows the refrigerant to absorb heat from the outdoor coil, effectively melting the frost and allowing it to drain away.

While other options like heating mode, fan mode, and emergency mode have specific roles in heat pump operation, they do not facilitate the defrosting process. Heating mode is focused on providing warmth to the indoor space, while fan mode simply circulates air without changing temperature, and emergency mode is typically intended for heating during malfunctions. Thus, switching to cooling mode during the defrost cycle is key to efficiently eliminating frost and maintaining optimal operation of the heat pump system.