Your AC unit naturally works harder when outdoor temperatures are high, resulting in increased utility costs as well as extra wear and tear on your system. Unfortunately, AC malfunctions often occur during heat waves, leaving homeowners sweltering until help can arrive in the form of an HVAC repair service. One of the common issues that occur is that the system completely freezes up. Here's why it happens and what you may be able to do about it:  

Dirty Evaporator Coils

Because evaporator coils are located in the outdoor sensor unit of your AC system, they're more vulnerable to the buildup of dust and debris than the parts that are situated indoors — and because condenser units are usually placed in out-of-the-way locations on the home exterior, such as the side of the house where no one ever goes, they're often the last thing that gets checked when something goes wrong. Accumulation of dirt, dust, debris, and airborne particulates, including mold spores, occurs naturally over time, and it essentially suffocates the coils and causes them to freeze up. 

Calling an AC repair service is the best way to deal with frozen condenser coils. Because mold may be a part of the picture in this situation and because the coils themselves are delicate, special handling and training are required for best results.   

Clogged Air Filters 

Clogged air filters are responsible for a wide range of HVAC problems, not the least of which is that the restriction of airflow they cause may result in not enough warm air blowing over the condenser coils, therefore causing them to freeze up. Additionally, clogged air filters result in airborne particulates such as mold spores, pet dander, and household dust getting distributed throughout the home, contributing to indoor air pollution and potentially being harmful to human health. 

Depending on the type of unit you have, air filters need to either be changed or cleaned on a regular basis. Check your owner's manual for step-by-step instructions on how to change or clean your unit's filter. If this doesn't solve the problem, call an HVAC repair service. 

Refrigerant Leaks  

Refrigerant leaks cause a decrease in refrigerant levels that result in lower interior pressure, resulting in very cold temperatures that cause the refrigerant line and the coils to freeze up. Besides obvious visual signs of a leak, you may also experience an unexplained hike in cooling costs as a result of a refrigerant leak. Because refrigerant is a potentially dangerous substance, it's very important that leaks and other HVAC issues involving refrigerants are only dealt with by trained professionals.

To learn more about ac system repairs, contact an HVAC contractor in your area.