Why Is My Air Conditioner Freezing Up? (4 Main Culprits)

Many times, we hear the question “why is my air conditioner freezing up?” This happens as a result of quite a number of reasons, we’ll discuss them in a bit. However, the main culprits are poor airflow and low refrigerant.

air conditioner freezing up
Courtesy: eglin.af.mil

Since air conditioners have the job of cooling a room , it’s easy to assume it is firing on all cylinders when you notice the freezing.

However, the reverse is the case, even though it most likely isn’t a serious problem. If unchecked, it might lead to serious damage.

It is important to regularly check on your air conditioner and service it. That way, the whole unit , and its parts will continue to work optimally.

As you keep reading, you’ll find out more reasons your air conditioning system might freeze. With that, you’ll be able to prevent it or call for help if it happens.

What Leads to an Air Conditioner Freezing up?

If any part of your air conditioner is freezing, then there is an issue with the unit. Air conditioning systems are not designed to behave like that, even though their job is to cool your home. The following are some of the issues you can suspect if the evaporator coil or some other parts of your AC unit is freezing up.

Low refrigerant

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A refrigerant is a liquid in the evaporator coils that absorbs the warm air in your home and dumps it outside. It has a low boiling point which is why it is able to do serve its purpose well.

When the refrigerant in the air conditioning system is low, the saturation point temperature of the entire system falls. This also causes the boiling point of the refrigerant to drop.

Ideally, the moisture-laden refrigerant is supposed to cool and deposit the moisture in a drainage pan. In this case, because of the fall in temperature, the moisture in the refrigerant becomes frozen on the evaporator coils.

Since the entire process that makes the air conditioner work has been halted, you will notice that your AC unit is not cooling the air inside anymore.

Dirty Air Filter

A quick question and you have to be honest. When was the last time you replaced or cleaned the air filters in your air conditioning unit?

If the air filters clog, enough air will not flow through the evaporator coil which will cause the temperature of the refrigerant to drop.

With no airflow to absorb the cooling, moisture condenses on the surface of the evaporator coil, just like it does on a chill bottle on your kitchen counter.

The low temperature then freezes the condensate. The longer the AC runs in this state, the more the freezing will spread. It can go as far as turning your compressor into a block of ice.

Damaged Blower Fan

The blower fan is responsible for proper airflow circulation in the air conditioner. So, if it is damaged or not working properly, there won’t be air blowing over the evaporator coil and that will cause freezing.

Dirty Coils

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The moist air in your home pulled into the coils is supposed to condense on its surface and drip into a pan. But if the coils are dirty, it will reduce the rate it can absorb moisture. If this continues, the coil will become waterlogged and freeze up.

Some other reasons your air conditioner might be freezing up are:

  • Setting your thermostat too low
  • Too many vents or return grills closed off
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Solutions to Freezing Air Conditioner

Once you notice your air conditioner is freezing up, the first thing to do is to turn it off. At that point, the AC is not doing any cooling anyway. Allow the frost to thaw. This will take a while but there are things you can do to speed up the melting.

If it’s a window unit, you can use a hairdryer to blow heat over the ice to melt it. If it is a larger system, turn your home thermostat to fan so it can blow some warm air. You should consider cleaning the air filters too.

Do note that depending on how much ice has built, it might take a day or two for it completely melt. The temperature outside has its influence too.

With melting ice comes water, so be sure to prepare for handling the resulting puddle. Finally, when it comes to repairing your air conditioner, it isn’t something you should do yourself.

Call an HVAC expert and tell them what happened. They probably will have to refill your refrigerant which you can’t buy without a license anyway.

Courtesy: kusan.af.mil


Air conditioners make our homes and offices a lot more comfy and enjoyable to pass time. But if you don’t care for and service them, you’ll be left wondering why the air conditioner is freezing up. Now that you have this information, you can take preventive measures and keep your AC unit functioning optimally for longer.

For more information about devices responsible for the quality of your indoor air, explore our website. Come back soon for fresh updates from your Air Xpert. Thank you for your time.

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