What can lead to ice build-up on evaporator coils?

Ice build-up on evaporator coils is primarily caused by factors that affect the coil's ability to effectively maintain the desired temperature and humidity levels. Low airflow, for instance, can prevent adequate heat exchange, leading to a drop in temperature on the coils that causes moisture in the air to freeze.

Refrigerant undercharging means there isn’t enough refrigerant circulating to absorb heat effectively, which can also lead to lower temperatures at the coils. Additionally, excessive humidity in the air can contribute to frost or ice formation, as the moisture condenses and freezes on the coils due to the temperature difference. Therefore, all these elements—low airflow, undercharged refrigerant, and high humidity—work together to create conditions that favor ice build-up on the evaporator coils.

The other options are less relevant to the core issue of ice build-up. While increased room temperature could potentially relate to energy loss, it does not specifically cause ice build-up in the same way as the correct answer. High airflow and refrigerant overcharging could lead to inefficient cooling but typically do not result in ice formation. High efficiency and overuse of insulation material do not directly lead to issues with evaporator coils in terms of ice formation.