What occurs during the defrost cycle of a heat pump?

During the defrost cycle of a heat pump, the system temporarily reverses its operation. This is necessary to address ice buildup on the outdoor coil, which can occur in cold or humid conditions. Typically, the heat pump is set to absorb heat from the outdoor air to warm the indoor space. However, when ice forms on the outdoor coil, it impedes the system's ability to transfer heat effectively.

By reversing the flow of refrigerant, the heat pump redirects warm refrigerant to the outdoor coil. This process warms up the coil, causing the ice to melt and ensuring that the unit can function efficiently once the defrost cycle is complete. This cycle is essential for maintaining optimal performance and energy efficiency, allowing the heat pump to continue heating the indoor space effectively.