What should be checked if an evaporator coil is freezing?

When an evaporator coil is freezing, this generally indicates a problem with airflow or heat transfer within the system. A blocked return can lead to inadequate airflow, which prevents the coil from receiving enough warm air to absorb the heat, thereby causing moisture on the coil to freeze. Maintaining a proper airflow is crucial, as any obstruction can significantly impact the efficiency of the heating and cooling process.

While low refrigerant can also contribute to freezing, its primary effect is usually related to pressure drops that cause the evaporator to operate at lower temperatures. A faulty compressor could result in refrigerant not circulating properly, but it would not directly cause the evaporator coil to freeze without other underlying issues like low refrigerant. The condition of the air filter also plays a role; a dirty filter reduces airflow, but checking the return specifically addresses the larger system's airflow issues. Focusing on the return duct ensures a comprehensive approach to resolving the freezing problem by confirming that air is effectively being cycled through the evaporator coil.