Four Reasons Air Conditioners Freeze Up

One of the most common questions our AC techs get asked is “Why does my air conditioner freeze up?” Although you may feel like you’re all alone when your air conditioning unit suddenly develops frostbite, it is a typical problem in any household.

Whether it’s a central air conditioning system or a window AC unit, causes of and solutions to freezing up are basically the same. The most important part is getting help for a frozen air conditioner. In addition to cooling problems, continuing to operate while its not working correctly produces severe damage. The unit goes through an involved process of expansion and compression to make cool air in your home and take hot air out. Something is out of balance if the evaporator coil is cooling too much, resulting in icing. It may be the Freon is expanding more than it should be, making the coils colder than usual. Another possibility is that something is keeping your home’s air heat from transferring into the system. The result is the same: the evaporator coil drops below freezing while the ac freezes up.


Here are four of the most common ways to keep an air conditioner from freezing.

1.Run the A/C within certain temperature parameters. Avoid using the air conditioner if it’s less than 62 outside. Otherwise, system pressure will drop, causing the central air unit to freeze.

2.Be sure the refrigerant is at the recommended level. The unit already has lower pressure and if there is less Freon than needed, the air conditioner must work even harder to expand. When the evaporator coil drops below freezing, moisture in the air freezes when it contacts the coil and ices up.

3.Have the unit maintained and serviced according to the manufacturer’s guidelines. It’s no surprise to hear that mechanical failure is a major cause of air conditioner problems, including freezing. A non-working blower fan, clogged filter, or kink in the lines that allow refrigerant to move properly also affect system pressure.

4.Have the ac checked to be sure enough air is blowing across the evaporator coil. The unit drops your home’s temperature by removing heat from the inside air as it blows over the evaporator coil. If the Freon is unable to work properly, it can lead to ice and damage.


An efficient HVAC system keeps homes warm during the winter and cool during the summer. It also helps remove dust and debris from the inside air, adding a healthy environment to your home. Ask your air conditioner technicians about steps you can take to make sure the unit is operating correctly. Never hesitate to call for service if you notice any of the above problems.

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