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Why Is My AC Evaporator Coil Frozen?

evaporator coil frozen

Your AC works hard during the summer to keep you cool and comfortable in your home. Have you turned on your air conditioner for the first time this year and found that your air conditioner is not producing any cool air? One cause for this is a frozen evaporator coil. What is an evaporator coil, and why does it freeze? You may think having a frozen evaporator coil is not a big deal and can make your AC colder. However, this is far from true, if the evaporator coil is frozen, then the air conditioning unit cannot do its job properly and your home will be warmer than usual. In this article, we discuss how the evaporator coil works, why it can freeze up and how to fix it.

How an Evaporator Coil Works

The evaporator coil works by absorbing heat. It removes the heat from the air to make it colder. In order for the evaporator coil to properly work as intended, the air needs to make contact with the metal coils so they can absorb the heat. Anything that blocks direct contact with the coils such as ice, will interfere with the way the evaporator coil works resulting in warm air.

What Causes an Evaporator Coil to Freeze?

Lack of Airflow

When the coils are not able to absorb the heat into the refrigerant is when things start to go wrong. This occurs because the return air is unable to get to the refrigerant line. As a result, the refrigerant begins to get colder with no heat to absorb. The line gets so cold that the condensation on the outside of the line freezes over leading to ice. Low airflow can be caused by multiple issues such as faulty blower fan, dirty air filters or damaged ductwork.

Dirty Coil

Over time your system’s evaporator coil will become covered in dust, dirt, and other debris. If your evaporator coil collects too much, the heat exchange process as described above becomes obstructed. Essentially it will prevent the air from making direct contact, leading to frozen evaporator coil as a result. Upon professional inspection during AC repair, evaporator coil cleaning may be recommended.

Refrigerant Issues

Having low refrigerant in your system can lead to a frozen evaporator coil. Low refrigerant causes the system to overwork which can lead to the condensation on the coils to freeze. If you have low refrigerant, it may be that it was never properly charged, or you have a refrigerant leak.

Dirty Air Filter

A dirty air filter can cause the same airflow issue as with a dirty coil as it will also restrict the airflow. A dirty air filter will prevent the evaporator coil from absorbing the necessary amount of heat from the air to function properly. Dirty air filters can also lead to other system components to failing. Routine AC maintenance is essential in keeping your system working properly and efficiently.

Blocked Ducting

Closing vents or registers can lead to insufficient return air flow from getting to the coil. Keep registers free from being blocked with curtains or furniture as well.  Be sure to keep registers open to allow for proper airflow.

Clogged Drain Line

Condensation on the evaporator coil is part of normal operation. However, if the drain line is clogged this can result in too much condensation that may develop on the coils, leading to a frozen evaporator coil.

Low Thermostat Setting

You may think setting the thermostat to a really cool temperature will lead to your AC achieving the set temperature faster. This is not correct, a thermostat that set to a low temperature can also sometimes cause a frozen evaporator coil. Setting the thermostat to a low temperature does not mean your air conditioner will work faster and it will not produce colder air.

What To Do if You Have A Frozen Evaporator Coil

The best way to prevent a frozen evaporator coil is through scheduling routine preventative maintenance. Regular HVAC maintenance is the most effective way to ensure your system runs efficiently and properly as long as possible. In between visits replace your air filter at minimum once every 3 months. If you do find yourself with a frozen evaporator coil the first thing you will want to do to minimize further AC damage is to turn off your air conditioner. Never chip away at the ice, let it melt naturally. Then contact a professional to find the cause of the evaporator coil and complete the appropriate repair or AC replacement.

Contact LA Construction, Heating and Air for AC Repair

The easiest step you can take is to schedule AC maintenance at least once a year. We offer different maintenance plans to fit your needs and budget. If you find yourself with a frozen evaporator coil or any other AC issues give us a call today or contact us online to schedule AC repair. We are ready to help you!

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