Common Causes Of Evaporator Coil Icing

When layers of ice form over your air conditioner's evaporator coils, the performance of your cooling system is likely to suffer. This is because ice is a poor conductor of heat, and when it forms over your coils, it reduces the ability of the coils to allow the refrigerant to efficiently absorb heat from the passing air.

There is also the fact that continued icing at the evaporator coils usually allows the coils to hold more water than they normally would. And when the ice eventually melts and all the accumulated water gets released into the condensate drainage system, the risks of air conditioner water leaks usually increase.

To ensure that your system doesn't suffer from icing-related performance drops and that your home is protected from air conditioner water leaks, finding and then fixing the cause of icing is a must. The following are common causes of air conditioner coil icing. Knowing them will come in handy in helping to trace the source of your problem.

Blocked thermostatic expansion valve

Impurities in the refrigerant can accumulate in the thermostatic expansion valve, which blocks it. Low refrigerant temperatures can also cause freezing to occur at the valve, something that may then limit the ability of the valve to allow the refrigerant to enter the evaporator coil area. When any of these things happens, the thermostatic expansion valve will let in less-than-required amounts of the liquid refrigerant into the evaporator coil. This will cause an abnormal drop in evaporator coil pressure, something that will then cause extreme temperature drops and result in evaporator coil icing. Replacing the blocked or frozen valve is usually enough to get rid of the icing problem.

Clogged air filters

After continued use, air conditioner air filters usually get clogged with debris, mold, and dust particles. These unwanted materials essentially turn the filters into air supply obstructions that then limit the amount of air that gets into the air conditioning system. This a problem since an adequate supply of warm air is necessary to keep the evaporator coil temperatures from dropping below the freezing point. And since the clogging of the air filters restricts the supply of this air, it plays a significant role in creating an environment that is conducive not only for condensation, but also for the freezing of any formed condensate. This is what then leads to evaporator coil icing.

Cleaning the clogged filters with soap and a bucket of water is usually enough to prevent evaporator coil icing. However, if the filters are worn-out, replacing them is the ideal solution.