Nothing is more frustrating than having your air conditioner coil freeze up just as the temperature outside is climbing.

Coils freeze when the temperature in your evaporator coil drops too low. Moisture in the air freezes on contact, building up ice on the coil. This buildup blocks airflow and can cause your unit to fail completely.

Why do AC coils freeze?

Low air flow prevents heat from being absorbed by the refrigerant in your evaporator coil. The temperature in the coil then plummets below freezing and ice accumulates. A dirty filter, malfunctioning fan or motor are possible causes of low air flow. Restrictions of any kind in your ductwork can also prevent the air from flowing across the coil.

A faulty thermostat can overwork your air conditioner, reducing the temperature in the coil to the point of freezing it. The unit's internal controls can also cause problems so have the entire control system checked.

Low refrigerant pressure results in a lower temperature in the evaporator coil as the refrigerant expands. This is typically caused by leaking refrigerant which must be repaired immediately.

How to prevent frozen coils

Clean and replace filters at least four times per year to maintain airflow across the coil. If you have pets or live in a dusty area, you'll have to change them more often.

Keep your blower fan and motor well-maintained to ensure that it blows enough air across the coil.

Check your thermostat and controls so the unit operates within its designed temperature