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How Do I Keep My Air Conditioner from Freezing up?

Relaxing inside your house in the summer is rejuvenating, thanks to the air conditioning technology. Without this, we can barely stay inside the house when the temperatures hit the roof. However, ACs need regular maintenance. You may have noticed the formation of ice on or inside the AC in your routine checks. And it is okay to get alarmed. Most homeowners, however, do not have sufficient info on how to handle this problem. When your AC is freezing, the ice may or may not be visible. If you think that your AC may be icing up, place your hand over the supply register. If it has ice, there will be minimal airflow. Luckily, the formation of ice in your AC can be solved, depending on the cause.

What causes air conditioners to freeze up?

1. Lack of airflow

This is the most known reason why your AC might be frozen. If anything in the system stops the warm air from flowing through the coils as the compressor works, your AC will start to freeze. Lack of airflow can be caused by:

  • A malfunctioning blower motor- If the blower motor stops functioning, the air will not flow through the coils. Once airflow is stopped, the coils will start freezing. And if not checked and repaired, the freezing will only get worse. You can identify an almost faulty blower if the AC starts to make rattling sounds.
  • Collapsed duct- The ducts guide the flow of air from the air conditioning system to the home. If they are blocks, then air cannot move through the system. Even if all other air conditioning components are running perfectly, you will experience countless issues, including AC freezing if the ducts are either blocked or collapsed.
  • Clogged air filters- You should never neglect the air filter. Regular checks will prevent most AC issues. Air filters easily get blocked since they sit between the AC and the dusty home vent. But when they fill with mold or dust, the flow of air is restricted, causing your AC to freeze.
  • Low fan voltage- Your home electricity voltage could be the culprit to your frozen air conditioner. Based on their capacity, ACs require a certain voltage to run efficiently. If the blower motor or fan is underpowered as the compressor runs, the AC might get frozen.

2. Low refrigerant

When was the last time you had the refrigerant levels checked?  The level of the refrigerant inside the AC coils affects how the AC works. When the refrigerant level is too low, the AC might start freezing. The low levels could be caused by an unidentified refrigerant leak, which is a big problem. If you think your AC refrigerant is leaking, contact an HVAC specialist immediately.

3. Blocked coils

The role of the AC filter is to prevent dust and other contaminants from reaching the inside components of the AC. If the AC is operating with a dirty filter, a low-quality one, or even without one, dust can build up on the refrigerant coils. If the dust blows past the damp coils, it forms a thick blanket that acts as an insulator that traps the cold air into the coils. The excessive amount of cold air can cause the AC to freeze.

4. Slow fan speed

The fan should blow fast enough to maintain the proper amount of air that blows over the evaporator coil. If you think slow fan speed is the cause of the frozen AC, request a technician to increase the fan speed. If this was the culprit, the frozen AC should clear up.

5. Improper AC placement

This is a common problem with window ACs. If the air conditioner is improperly tilted towards the window, it might freeze up. Ensure the AC is tilted in such a manner that the indoor portion is placed slightly higher than the outdoor half. Improper placement restricts water from exiting the drain hole. Instead, the water rests in the AC, causing it to freeze.

How to prevent an air conditioner from freezing

    • Have an HVAC technician check the refrigerant levels regularly– Low refrigerant levels are the most common causes of frozen air conditioners. With the low levels, the unit will attempt to run on less refrigerant. The result? A drop in pressure which in turn causes the evaporator coil temperatures to drop below the freezing point. The technician will check for possible leaks in a component that handles the refrigerant or the refrigerant lines.
    • Replace the air filters– Dirty filters are the common culprits to most AC issues. Luckily, you can inspect, clean, or even replace the air filters even without the help of a technician. Not only will regular air filter replacements avert AC freezing issues but also improve the quality of air in your home. Most experts recommend replacing the filters every three months. However, depending on environmental factors and how often the AC is used, you can replace the filter after every month.
    • Check the AC vents for blockage– Inspect the supply and return vents and ensure that they are not blocked. To prevent vent issues, move any furniture or home appliances that could restrict the flow of air through the vents.
    • Inspect the condensate drain line– Air conditioners cool spaces by absorbing heat and transferring it to outdoor spaces. If any condensed moisture is trapped in the condensate drip tray with a clogged system, the water may eventually overflow and cause the AC to freeze. If the condensate drain line is blocked, you can use the suction power of a dry or wet shop vacuum to remove the trapped debris. If this fails, contact an HVAC technician to inspect the system.
    • Check your blower fan and ensure it’s working efficiently– If the blower fan can’t generate airflow to prevent the coil from freezing, you might have endless AC issues. Contact a HVAC specialist to inspect the blower fan and check the wear and tear condition, the rotational speed, direction and power output.
  • Ensure the window units maintain the correct angle.  

Final thoughts

You should take measures to prevent your AC from freezing. However, do not be alarmed if your air conditioning system freezes. The best preventive measure is to have an overall maintenance check by your HVAC technician. This way, they can identify and sort issues that may cause your system to freeze and prevent serious AC damage. 

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