The defrost cycle is a necessary operation for any heat pump where the system temporarily reverses to melt frost that has accumulated on the outdoor coils. During this short period, the outdoor fan stops and the unit sends heat to the exterior coil to clear the ice. This is a completely normal part of operating heat pump systems in temperatures below 40°F. Our modern inverter technology ensures these cycles are as short and efficient as possible to minimize temperature fluctuations. If you find your unit isn't heating well in the winter, checking the heat-pump-condensers for excessive ice buildup is a good first step. Proper drainage from the base pan is essential for a successful defrost process.