What maintenance tasks are essential for HVAC system efficiency?

Maintaining HVAC system efficiency is crucial for ensuring optimal performance and energy savings. Regular filter changes and cleaning coils are essential maintenance tasks because filters that are clogged can restrict airflow, leading to reduced efficiency and increased strain on the system. Clean coils are vital for heat exchange; dirty coils cannot transfer heat effectively, which can further diminish system performance.

In addition to these tasks, checking refrigerant levels and inspecting ductwork are equally important. Proper refrigerant levels are critical for the HVAC system to cool or heat effectively—too little refrigerant can lead to system inefficiencies and potential compressor damage. Ductwork inspection ensures that there are no leaks or blockages that could disrupt airflow and reduce the system's efficiency.

By combining both regular filter changes and coil cleaning with refrigerant and ductwork checks, a comprehensive maintenance routine is established, leading to improved lifespan, reliability, and efficiency of the HVAC system. This holistic approach is precisely why the correct answer encompasses both sets of maintenance tasks.