Why is ice forming on the cooling coil and what should I do?

Ice forming on the cooling coil can be caused by outdoor temperatures below 60°F (16°C), a dirty dust filter, a dirty PureAir filter, or a temperature setting that is too low for nighttime cooling. To defrost the coil, set the unit to FAN ONLY mode, then clean or replace the filter as needed and adjust the temperature to a higher setting. (Page 22)