What effect does dirt on an evaporator coil have on its performance?

Dirt on an evaporator coil acts as an insulator, which significantly hampers the coil's ability to effectively transfer heat. When dirt accumulates, it creates a barrier between the air and the coil's surface, preventing optimal heat exchange. This insulating effect leads to less efficient cooling, as the coil cannot absorb heat from the air as designed. Consequently, the system may have to work harder to maintain the desired temperature, resulting in increased energy consumption. In some cases, this inefficiency can lead to further issues such as reduced cooling capacity or even the risk of ice formation if the coil temperature drops below freezing due to impaired airflow. Therefore, keeping the evaporator coil clean is essential for maintaining effective HVAC system performance.