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What Causes an AC to Freeze Up?

frozen evaporator coils

While you might think ice buildup on your AC is a sign that it is working, it’s actually a sign that it needs to be repaired right away. During summertime, it is common for air conditioners to get overworked and experience malfunctions that can lead to frozen evaporator coils and other types of serious damage. At Lex Air Conditioning and Heating, we recommend becoming familiar with the most common causes of AC freezing so that you can take the necessary steps to avoid this problem. Keep reading to learn more about what might cause your air conditioner to freeze and what you should do about it.

Common Reasons for Air Conditioner Freezing

The evaporator coils on your inside AC unit contain refrigerant that is used to cool the air being sent into your home.

There are a variety of problems that can cause the evaporator coil on your air conditioning system to freeze up, including:

  • Lack of airflow: Your evaporator coils are filled with refrigerant, which is used to create cool air. Warm air is sent over the evaporator coils to simultaneously prevent the coils from freezing over and provide the coils with air that can be cooled and sent inside. When your AC’s air flow is restricted, the evaporator coils are not warmed by the air, which causes them to freeze over. A lack of airflow can be caused by a clogged or dirty air filter, broken or undersized ductwork, blocked air vents, or a damaged blower fan.
  • Low refrigerant levels: Low refrigerant levels, caused by refrigerant leaks, can cause a drop in pressure in your AC. These leaks can occur in the refrigerant lines, coils, or other components of the air conditioning unit. The resulting pressure drop can cause the evaporator coil temperatures to drop below freezing, forming layers of frost until the coils are coated in ice.
  • Dirty coils: When your air filters are low quality or clogged, it can send excess dust into your air conditioner. This excess dust can build up on your coils until they are encased in them. This layer of dust acts to insulate the evaporator coil, which restricts airflow and causes the coil to freeze over.
  • Fan speed: Your fan’s rotation speed should be fast enough to ensure the appropriate amount of cooled air is blowing over your AC’s coils. If the fan speed is insufficient, it can not only cause poor airflow but also lead to AC coils freezing. 
  • Blocked drain line: Your air conditioners evaporator coil removes excess moisture from the air. This moisture-turned-water vapor is then caught in a drain pan. As you can imagine, if there is something blocking the drain line, nearby water vapor will freeze and cause even further blockage of the drain.

What to Do If Your AC Is Frozen

If your outdoor air conditioner freezes, it is important that you call a qualified Carrollton AC repair technician right away. A frozen AC unit is a sure sign that something is wrong with your system, and ignoring this issue could lead to a complete system breakdown.

While you wait for your HVAC professional to arrive, turn your thermostat off, but leave the fan on. Keeping your thermostat set to cool will force your HVAC system to endure more strain and increase the risk of further damage. Instead, setting the fan to “On” while keeping the cooling setting off can add airflow that can start to melt the ice on your AC coils.

How to Prevent Your AC Unit Freezing

Air conditioners freeze for a number of reasons, but most of these causes can be prevented with proper routine maintenance. To recap, the following problems are what causes an air conditioner to freeze up:

  • Dirty air filters: As you know, clogged filters impede airflow, which can lead to ice formation on your AC system. This is why it is so important to change air filters regularly. AC filters should ideally be changed once a month for maximum HVAC efficiency and to prevent frozen AC coils. 
  • Faulty blower fan: Just as dirty air filters can lead to frozen air conditioners, so can a damaged or malfunctioning blower motor. If you believe a faulty blower fan to be the culprit of your AC freezing, call an HVAC professional at Lex Air today for an inspection.
  • Refrigerant leak: Leaking refrigerant can be dangerous and cause a plethora of problems with your HVAC unit. If you believe your refrigerant line is leaking, be sure to call an HVAC specialist to repair the problem.
  • Dirty coils: Having your HVAC unit inspected and cleaned regularly can prevent dust buildup on your coils, and thus, prevent a frozen AC line. 
  • Poor fan speed: If your HVAC unit’s fan speed isn’t fast enough, an HVAC technician will be able to identify this and increase the speed to ensure your unit does not freeze up. 
  • Drain line blockage: During warmer weather, it is important to regularly check and clear the drain pipe to prevent ice buildup. Ideally, this should be done once a week.

Lex Air is There for All Your HVAC Needs

A frozen AC is a serious problem, but it can be fixed if it is early on. At Lex Air Conditioning and Heating, each of our technicians has undergone extensive training and is fully qualified to handle your every heating and air conditioning need. If your AC is frozen, we will be there in no time at all to discover the source of the problem and get your system back up and running.

Our air conditioning services include:

Frozen Air Conditioner? Call a Professional Carrollton HVAC Technician at Lex Air Conditioning and Heating Right Away

Is your AC unit frozen? The HVAC experts at Lex Air can help. Backed by 30+ years of service excellence, you can count on Lex Air Conditioning and Heating to implement a reliable and lasting solution.

To learn more about how we can take care of your home, please call (972) 217-8955 or send us a message online.

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