Air conditioner

4 ways to fix outside frozen AC unit in winter

If your concern is a frozen AC unit outside, this article is for you. One of the most common problems that house owners experience about their air conditioners is a frozen AC unit installed outside. If you are one of those people who has preferred the AC unit out and living in a place where the winter is brutal, you are more likely to think that the AC unit freezes up because of the low temperature. However, a frozen AC unit outside is not the result of a bad weather condition but of more complex technical issues. It is estimated that almost every house owner faces this problem at least once in his/her lifetime.

Whether your Ac unit is frozen right now or you want to prevent trouble in advance, we recommend you keep reading this article we have prepared to help you. Directly below, we have discussed the main reasons why an air conditioner keeps freezing up and the ways how to solve this problem or even avoid before it happens.


What Causes an Air Conditioner to Freeze?


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Although the reasons why an air conditioner puts on ice are numerous, it is vital to understand the working mechanism of the AC unit. Due to our physics classes at school, we already know that when the gas expands, the pressure and consequently the temperature declines. Of course, it applies when everything else stays unchanged. We call it the Joule-Thomson Effect.

When it comes to the working mechanism of an air conditioner,(TOO LONG) as its primary duty it gives out fresh air into your house and throws the heat outside. When this equation breaks, the air conditioner may put on ice. Various parts can violate the balance. However, if not maintained on time, the unit can get destroyed. Let’s have a more in-depth look into the main possible culprits that make an air conditioner stop working.


Blocked or Limited Airflow


When the airflow is blocked, it poses a potential threat to the cooling system and heating system. When the airflow is limited or blocked the number of hot air decreases, and the temperature falls to the freezing level. Eventually, as the high in moisture air contacts with the coils, it builds upon it and freezes. The point is that there are also various factors which can lead to airflow obstruction, such as dirty air filters, evaporator coils or clogged vents. Right below, we will discuss all these problems in details.


Dirty air filter


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When the debris is built on the air filters, it causes even more severe problems that a frozen AC unit outside. It is terrible for your health, pocket, and comfort. If you are not careful about the spare parts of your AC unit or every time you postpone the maintenance because of some reasons, you are more likely to face this problem.

As time passes, the air filters get covered with dust, and because of this reason, the unit starts working hard by using more energy. It is no doubt true that the more power it uses, the higher electricity bills you get. Moreover, the dust prevents the device from working correctly and being able to remove heat. As a result, you experience a frozen AC unit problem installed outside your house.


Dirty evaporator coil


Like air filters, evaporator coils are also vulnerable against dirt. If you do not clean or replace this part on your cooling system, gradually it will put on dust. Dust pile on an evaporator coil means an improperly operating AC unit because it prevents the air flow and causes ice aggregate on the loop.


Blocked return ducts


If you are feeling a dusty smell in your house or the energy consumption has eventually increased, most probably the reason is the blocked air ducts. When the pipe is not cleaned for a long time, it piles up debris which causes the blockage. Consequently, the air conditioner loses its proper operating condition and starts to work harder to reach the temperature you have set.


Closed vents


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Closing the vents is another issue which puts your air conditioner at risk. When a room is cooler than the others, some people turn some vents off. However, it makes the conditioner push the limits and use more energy than it is supposed to take. The reason is that when you close the vents, the open ones have to work harder to overcome the pressure created by the closed ones.


The blower fan is not working


One of the most common reasons for a frozen AC unit outside is improperly working blower fan. Since the primary duty of a blower fan is taking the air to where it is supposed to go, it causes problems when it is broken. If the blower is broken, it will change the direction of the air flow. Misdirected airflow will cause condensation on the coil and contribute to the freezing.


Refrigerant is Low


This problem is mainly associated with the old version of refrigerant. Since this type is much more prone to freezing, most of the house owners prefer a new model which is called R410. It is still possible to experience a freezing problem with air conditioning system even if its refrigerant is modern. In this case, you should examine all the fittings and look for a leak. In case you cannot spot the hole, you can use a refrigerant color.




There are some primary steps to be taken before getting the fixation process to start. First, you need to turn the AC unit off and let it defrost. Then you should change the air filter. The next step you should follow is turning on all the registers at home and ensure that the vents are open. If the air conditioner still keeps freezing, only then you can start thinking about a more serious fixation.


It is important to note that the defrosting can take around a day and it is not a good idea to clean the ice by hand. After all, the ice goes away, dry the coils. It is also possible to turn the blowing on to fasten the melting process. Never keep using an AC unit if you think that it might have put on ice.


Check the Vent


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If you are still experiencing the same problem, one of the steps you should take is checking the vent. If it is dirty, possibly, it is clogged. The debris clogged the vent prevents air flow and causes the air conditioner to freeze.


Check the Coils and Fins


If the coils and fins seem dirty, you should gently clean it out with a brush. Since the coils and fins are delicate parts, you should be extra careful to avoid damage to them. Cleaning them is crucial because once they get dirty, the dirt on them restricts the registers and causes freezing.


Check the Refrigerant


Checking the refrigerant levels is another way of solving this problem. When the refrigerant level is too low, it causes icing.  If there is a chance of a refrigerant leak, you should call for professional help.


To Fix or To Replace


If you are in two minds about fixing a frozen AC unit outside or replacing it, the main factor to consider is the cost. In case your AC unit is old, or the damage is quite expensive to repair, you should think of replacing it. However, if it is minor damage which will cost you a little, then the best option is calling for professional help.