What is a key maintenance task for heat pumps during the winter season?

A key maintenance task for heat pumps during the winter season is checking for ice buildup on the coils. In cold weather, heat pumps can experience frost or ice accumulation on the outdoor coils, which can impede their ability to transfer heat effectively. Monitoring for ice buildup is crucial because ice acts as an insulator, decreasing the system's efficiency and potentially leading to system failure if not addressed promptly.

If ice does form, it can also lead to additional issues, such as compressor damage or increased energy consumption as the unit struggles to maintain the desired indoor temperature. Regular checks, and possibly implementing a defrost cycle, help ensure the heat pump operates efficiently throughout the winter.

The other options do not address critical maintenance needs specific to the winter season. Replacing the refrigerant monthly is unnecessary and impractical, increasing thermostat settings doesn't directly influence the heat pump's performance, and inspecting ductwork for leaks is important but more general maintenance that is not specifically tied to winter operations.