5 Reasons Why Your AC Is Freezing At Night

Now that temperatures are heating up, we are starting to see an increased number of calls from homeowners with air conditioner freezing as their problem. We usually get the call after the homeowner goes outside to see why their AC is not cooling and discovers that the outside unit of their air conditioner  freezing up into a solid block of ice. Regardless of the type of air conditioner, most cases of air conditioner freezing can be attributed to a handful of causes.

infographic showing why your house might be cold
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Insufficient Air Flow

If there is not enough air flowing through your air conditioning system, your evaporator coil will eventually freeze up and cause your AC unit to freeze up and stop working. The most common cause of this is a dirty air filter. Dirt can also collect on the evaporator coil itself causing it to become clogged. This typically happens if the AC system was allowed to run without a filter or if the filter used was extremely dirty, too small for the system, or of poor quality. Air flow problems can also be caused by a faulty fan or closed or blocked ducts and vents.

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Low Refrigerant

If you find yourself having to add refrigerant to your air conditioner once or twice a season, it is a safe bet that you have a leak somewhere within the system. Leaks can develop as parts vibrate or rub together over time or when joints or fittings become loose. A leak can cause the pressure within the evaporator coil to drop. Moisture then collects and freezes on the coil. The ice continues to build from the inside to the outside of your air conditioner until it can no longer function.

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Air Temperature

The outdoor air temperature needs to be within a certain range in order for an air conditioner to run effectively. Even an AC that is in perfect working order may not run well if the outside air temperature is too low. When the AC is allowed to run when outside temperature is too cool, the pressure inside the system can drop and cause home AC freezing up. This is a common problem here in Colorado, especially during late spring and early summer when daytime temperatures can be quite warm but the nights are still very cool.

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Defective Blower Motor

Your air conditioner may freeze up if the blower motor is not running along with the rest of the system. One sign that you may have a defective blower motor is that the outside portion of your air conditioner will run, but the indoor portion of the system does not work at all.

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Stuck Contactor

A small part on the outside portion of your air conditioner called a contactor can become stuck. This allows the outside unit to run continuously so that it will eventually freeze up. You can see if this is the problem by turning your air conditioner off at the thermostat. If the outside unit continues to run even when the thermostat is off, you most likely have a contactor that is stuck. The only way to turn off the system in this situation is to shut it off at the circuit breaker.

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How To Prevent Your AC From Freezing

Most causes of air conditioner freezes can be prevented with basic maintenance and regular tune-ups. We recommend that homeowners in Loveland, Fort Collins, Longmont and the surrounding areas change the filter in the air conditioner on a regular basis. Depending on the type of filter that you have, filters should be changed every one to three months. You may want to do this more frequently if you have had recent construction in your home or have pets since these can increase the amount of particulates in the air. You should also consider turning off your air conditioner and opening up your windows if the nighttime temperature is forecasted to drop below 60°F.

At Swan, we also offer local residents an affordable AC tune-up package. Our technicians will clean, inspect, and test more than 20 of your air conditioner’s operating and safety features to ensure that your AC runs reliably and efficiently for years to come.

What To Do If Your AC Freezes

If your air conditioner keeps freezing up, you should turn it off immediately. Not only does continuing to run your AC not do any good, but it can cause substantial damage to the system. Other than checking for a dirty air filter, diagnosing and repairing the problem should be left to an HVAC professional. Trying to clean, replace, or repair any of the other components yourself can cause further damage and even void your manufacturer’s warranty.

Dealing with a frozen AC also requires a certain amount of patience. Just like an iceberg, the ice that you see on the outside of your AC unit is just a part of the problem. If there is ice that you can see, then the inside of your air conditioner is a solid block of ice that can take several hours to melt even in the heat of summer. Once you are able to turn on your air conditioner, it can take several more hours for the inside of your home to reach a comfortable temperature.

At Swan Heating & Air Conditioning, Inc., your family’s comfort is our number one priority. Call today to schedule your annual AC tune-up. Our professional and highly-trained HVAC technicians are also available 24 hours a day for all of your emergency air conditioning repair needs.