Which of the following conditions can lead to frost formation on evaporator coils?

Frost formation on evaporator coils is primarily linked to low airflow conditions. When the airflow across the coils is inadequate, the refrigerant within the evaporator does not have sufficient heat to absorb from the air. This lack of heat transfer can lead to the temperature of the coil dropping below the freezing point of water, resulting in moisture from the air freezing on the coil surface.

In a properly functioning air conditioning system, the evaporator coils are designed to handle a certain volume of airflow to effectively exchange heat. When airflow is reduced—due to clogged filters, blocked ducts, or insufficient fan operation—the coil does not operate efficiently, promoting frost build-up instead of normal operation.

High refrigerant flow, excessive heat load, or a correct refrigerant charge typically do not cause frost formation. In fact, high refrigerant flow or a correct refrigerant charge might enhance the evaporator’s ability to absorb heat, while excessive heat load would increase coil temperatures, which are contrary conditions to frost formation.