3 Reasons Your AC Unit is Freezing Up & What To Do About It


One of the reasons your AC unit may not be functioning properly is that it keeps freezing up. Minnesota residents know what it’s like to deal with the cold, but your AC freezing has nothing to do with our climate.

Freezing can be seen within the evaporator coil, or on the exterior of the outside unit (the condenser coils), and will appear to be covered in a thin layer of ice due to frost having built up on the refrigerant lines. So you’re probably asking yourself, “what causes an AC unit to freeze up, and what can I do about it?” The culprit is usually one of the following:

  • Inadequate airflow – When too many vents are closed or the air filter is dirty enough to block proper airflow throughout the system, an AC unit can freeze up because it can’t work correctly. The buildup of cold air can result in the refrigerant condensing on the coils.
  • The setting is too cold – Not all air-conditioning filters and units are intended to run at extremely low temps for prolonged periods or when it’s cool outside. Especially if the outdoor air is below 60℉, the air pressure won’t work correctly. Installing and using a smart thermostat can help you better understand the temperatures you’re using for what periods of time, and adjust accordingly.
  • Improper Freon Levels – If your system is too low or too high on Freon (refrigerant), it could cause the temperature of your evaporator to drop, freezing moisture and thus icing up the system. This could be due to a Freon/refrigerant leak that a contractor will need to repair.

What to do When Your AC Unit Freezes Up

Now that you know what may be causing your AC unit to freeze up, how do you go about diagnosing the issue? For starters, check the air filter to ensure it isn’t causing the issue. If it’s clogged, simply replace it and your problem should not persist. Also try unblocking vents. Sometimes household furnishings such as furniture and drapes can get in the way, causing the cool air to be pushed back through the system. Otherwise, it could be a Freon problem (leak) or the fact that you’re simply running the system too long for too long.

Important note: Before a repair can be done, you will need to defrost the system. Run the system with the fan on, but the AC off for 24 hours then call the home air conditioning repair experts at Sedgwick.

For a proper diagnosis as to why your AC unit keeps freezing up, and to get your HVAC system back in topnotch shape, contact the experts at Sedgwick. We have been in the AC business for decades and know what your home cooling system needs so it’s in tiptop shape this summer.

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