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Why are my AC Coils Freezing Over?

Why are my AC Coils Freezing Over?

At the height of summer, especially in Texas, the last thing you want is for your air conditioning to go out. It will threaten your comfort, probably threaten your health, and might even threaten your life to have to deal with living, working, and sleeping in temperatures above eighty or ninety degrees. 

Answering why your AC coils are freezing over requires one to understand what an AC coil is and how they work. The first thing you need to know is that the part of your AC that is freezing is called the “evaporator coil” and is responsible for transferring cold air into the air your air conditioner has taken in.

Since the evaporator coil deals with so much cold air it is no wonder it freezes. But it is not built to freeze, so what causes an evaporator coil to freeze? Well, here are three common reasons.

  • Poor airflow

The most common reason an evaporator coil freezes is because the air in it is moving too slowly. If the air in an evaporator coil moves too slowly then that means that rather than the cold air removing heat from the hot air the air conditioning is taking in, it is moving slow enough to remove heat from the air around the coil.

When that happens, the moisture outside the coil freezes, which only slows everything down more. Poor airflow is usually caused by a dirty air filter. This can also be caused by a malfunctioning fan.

  • Blocked condensate

This is an issue that usually arises when the thermostat is set far, far lower than it should be set. The condensate line is responsible for draining away moisture from the whole system of air that the air conditioner works with. This line of condensate can be frozen if it gets too cold.

Freezing this line causes a blockage, and a blockage means that the transfer of moisture out of the air conditioner will be slower. That usually results in a frozen evaporator coil, as any moisture nearby that coil will freeze if it is not moved away from it fast enough.

  • Thermostat Malfunction

This is the cause of frozen coils that is most likely to become a problem over time, as compared to the other two which tend to be a problem immediately. A thermostat malfunction means that the temperature that the thermostat reads in the AC and the actual temperature of the AC is different.

This will lead to problems because it will mean that the AC will run for too short or too long. Running too long causes it to freeze while running too short means you are going to be living in uncomfortable heat. 

These are the three most common ways an evaporator coil can freeze. Luckily, these are all well understood and easily fixed with just a little professional help. So, if you find your AC has frozen on exactly the hottest day of the summer, do not be afraid to call.