What Causes Frozen A/C Evaporator Coils?

On a central air conditioner, the evaporator coils are located inside of the home. When the air handler blows warm air over the coils, the refrigerant inside the coils absorbs the the heat, lowering the temperature of the air that is blown through the home’s air ducts. In addition to cooling your home, an air conditioner also dehumidifies the air. During the process of dehumidification condensation builds up on and drips off of the evaporator coils. This condensation is normally collected in a pan and drained away. When the condensation on the evaporator coils freezes, it can prevent your home from cooling properly and could lead to system breakdowns. So what causes the evaporator coils to freeze? Here are few possible causes:

1. Airflow Problems. When there is not enough return air blowing over the evaporator coils, the coils won’t have enough heat to absorb and can start to freeze. Airflow can be limited by a clogged air filter, leaking air duct leaks, blocked air registers and other causes.
2. Dirty evaporator coils. A dirty, unmaintained air conditioner will gradually result in reduced efficiency and uneven cooling. As the coils become covered in dirt they can’t absorb the heat from the air and the result is frozen coils.
3.  Low Refrigerant Levels. When refrigerant levels are too low as a result of a leak, the coils will not be able to absorb heat from the air, which can cause them to freeze up.

Have frozen evaporator coils? First turn the air conditioner off to allow the coil to thaw and prevent damage to the system. Next, call ABC Southwest Plumbing & Air Conditioning. We can diagnose the cause and get your air conditioner up and running again quickly.