20 Apr. 19

How to fix a frozen air conditioner


You already know that heating and cooling are essential for your home. You cannot afford to lack a heater when it is frigid, or an air conditioner when the weather is scorching. To enjoy your HVAC system, you need to understand them well. If you want to enjoy optimum use, understanding how they work becomes a necessity. In this article, we take on air conditioners, why they freeze up and how to fix the situation.

More often than not, we get asked the question “why is my air conditioner freezing?”. If you are facing the same problem, do not fret, it is not uncommon. Air conditioners getting frozen can result from several reasons. Although figuring out what causes your air conditioner to freeze up can be frustrating, it is vital that you try to fix it as soon as possible. A frozen air conditioner would not fix itself, and in fact, can lead to further complications if not quickly addressed. You should note that whether or not it is a split AC unit or a central air conditioner, the problems and the solutions are the same.

Safety first

If your air conditioner is freezing up, the first course of action is to put it off. This would help the thawing process. Alternatively, you can even turn the thermostat to the heating level to fast track the process of thawing. But before we delve into fixing your frozen air conditioner, it is important to understand how your air conditioner works.

How an air conditioner works

Many people are bothered by how their air conditioner works. While some do it out of curiosity, others do it so troubleshooting their air conditioners can be made accessible to them. An air conditioner works pretty much like your refrigerator. Your refrigerator pulls in heat, uses its refrigerant to cool it and uses the resulting cold air to cool its contents.

Similarly, your air conditioner creates a soothing atmosphere in your home through two coils. They are the evaporator coils and the condenser coils. The evaporator coils pull in humid air from the surrounding, cools the air, and then redistributes it around your home. While the air conditioner passes chilled air into your home, it passes hot air to the outside. These coils are the essential components which allow your air conditioner to cool your home consistently.

In the process of transforming the temperature of the air, however, complications may arise. These complications hinder the effective use of your air conditioner. One of such complications is the freezing of your air conditioner.

In understanding the reasons causing your air conditioner to freeze, there is a subtle need to understand a bit of physics. Do not be fazed; it is a very understandable and straightforward part of physics. In thermodynamics, there is a principle called the Joule Thompson effect. The principle states that as the gas expands, its pressure decreases, and its temperature increases. But when gas gets compressed, temperature increases. With this principle, you can better understand why your air conditioner works using the evaporator coils.

Why is my air conditioner freezing up?

Now that you have a good grasp of how your air conditioner works, we can proceed to discuss the causes of a frozen unit. You should know that your air conditioner can freeze up because of many reasons. Many of the times this happens, it is because a specific situation is causing the gas in your air conditioner to expand more than necessary thereby causing the air-con to freeze. On the other hand, it could be that a component or clog is preventing the passage of heat to your air conditioner system. When any of these two occurs, your system is bound to get frozen.

Other factors that may cause your air-con to freeze include:

  1. Hindrance of proper air-flow
    Your air conditioner is built to absorb the heat in your house. If there is a problem in the way your air conditioner exchanges the air in and out of your home, a problem could arise. For instance, if your air conditioner is not adequately blowing air over the evaporator coils, its temperature will continue to drop. This would gradually amount to a freezing up of the air conditioning system.
  2. Inadequate refrigerant
    The refrigerant is an essential element to the proper functioning of your air conditioner. While most people have the thought that it is a liquid, in particular, it is a combination of liquids.  It is used in several HVAC systems. The refrigerant performs its workings within the inside and outside unit of your air conditioner. Without the refrigerant, the evaporator coil cannot properly absorb heat from the surrounding.

So, now you know that the refrigerant is responsible for the cooling effect distributed by the air conditioner. As a result, when the pressure reduces in your air con, the refrigerant reduces as well. But if the system is still being coerced to produce the same amount – it would lead to more expansion. This increased expansion will lead to the freezing up of your air conditioner in no time.

  1. Mechanical failures
    Since your air conditioner is a system that has several electrical components, mechanical failures can arise. There are several mechanical components present in your air conditioner namely; compressor, fans, condensers, evaporators and so on.

The condenser, for example, helps in the exchange of heat in and out of the air conditioner. It transforms the temperature of the air thereby cooling it down for the fan to blow. While the condenser does that, the compressor serves the primary purpose of causing the refrigerant to be heated so that it leaves the compressor very hot.

Any of these mechanical components can fail and cause complications. For instance, if your fans stop working or they start malfunctioning, the pressure in the system will be affected, and this could effectively freeze up your air con. Similarly, if you notice that your condenser is functioning well, but your air conditioner is blowing warm air, this is a sign of a faulty compressor.

  1. Temperature 
    The way air conditioners are designed, they are designed to work at specific temperatures. So when this temperature suddenly becomes altered, it affects the pressure of your system. This can cause systematic freezing of your central air conditioner.
  2. Air filters
    Your air conditioner is designed with filters. These filters are usually made from fibreglass material or cloth. Through their little tiny holes, they serve the purpose of cleansing the air that moves around your heating and cooling system. When filtration occurs, the air is forced through the filter thereby causing contaminants to be removed from the air.

However, these filters are designed to trap dirt and therefore get clogged over time. This is why they need to be regularly serviced by bringing them out and cleaning them thoroughly. For effectiveness, you should have a regular maintenance schedule.

Can I fix my frozen air conditioner?

It is not every time your air conditioner malfunctions that you may have the opportunity to call in your HVAC contractors. There are several things that you can do to fix your air con. You can very well troubleshoot your system if you find it convenient to do so. But if you do not feel comfortable enough, you are advised to put a call through to your HVAC experts as soon as possible.

When troubleshooting a frozen air conditioner, follow these simple steps:

  • Just like trying to fix any other HVAC system, the very first thing is to put it off. When you put off a frozen air conditioner, it has time to defrost thereby reducing potential complications. There on, you can then follow the next steps in fixing the bug.
  • First, you are advised to never run your air conditioner when the temperature is below is 62°F. This is something you should take note of. Running your system when the temperature is below that figure can lead to significant faults. So, if you have been doing so, stop it, and see if that solves the problem. If it does not, look to the next step.
  • The next step involves fixing the airflow problem. Your heating and cooling systems depend largely on adequate airflow. In fact, airflow is the crux of their work. So, when air gets hindered, it leads to several problems.
  • If the AC is freezing up, check your air filter: Do not be casual with your air filter as the efficiency of your air conditioner is connected to it. In whatever you do, ensure that your air filters are of high quality as they are designed to be more robust and durable. Also, ensure that you change them regularly. Depending on the frequency of usage, this should be every 1- 3 months. If you do not do this, your air filter could easily get clogged. When this happens, the temperature drops below required levels which causes your air con to freeze up.
  • If your AC is freezing up, check your evaporator coil:  Since your evaporator coil is responsible for pulling air for the sake of cooling it, it deserves regular maintenance attention. Lack of airflow can result from a dirty evaporator coil. When this occurs, it can result in a decrease in temperature levels which causes your system to freeze
  • If your AC is freezing, check your ductwork: The ductworks are also essential to your cooling system. It is essential that you check your ductwork to ensure that there are no leaks or disconnections. Anything of such nature can disturb the flow of air and result in the situation of a freezing air conditioner.
  • If your ductwork, however, is in order, check for a build-up of dirt in them. To do this, you would have to check within the ducts which involve opening them. You are advised to seek help if you have not done it before or simply call in a professional.

It is possible that after doing all these, your air conditioner may still be freezing constantly. In that case, your best course of action is to call an HVAC professional. It possible that the internal faults in your system run deeper; a fact that can only be diagnosed by a professional.

The persistence of freezing can be caused by more in-depth problems like low refrigerant. This kind of problem can only be solved by an accredited professional who is licensed to recharge refrigerants.

Stay informed when buying your next air conditioner

We do not guarantee that the above fixes are definitely going to help out. They are possible fixes that have very high probabilities of solving your problem. If you, however, do everything and yet the problem persists, it may be that your air conditioner is old.

Before buying a new system, take careful steps to study the specs of the HVAC system. One of such careful steps is talking to your local HVAC contractor first. Your contractor can apprise you of the regulations in your area. An HVAC expert can also point you towards a system that fits your power bill and the size of your home.


We have been asked several times “how can I fix a freezing air conditioner?”, “why is my air conditioner freezing?”. To this end, we sincerely hope this article sets your path straight as regards those questions. Fixing your freezing air conditioner is important because a frozen air conditioner can damage your unit. When ice collects over any HVAC system, it has the potential of expanding and eventually damaging them. Therefore, to avoid unnecessary expenses, you have to adopt a healthy maintenance attitude.

Looking at your frozen air conditioner would not solve the problem. Summarily, turn it off, and follow the above steps towards solving it. If eventually, that does not work, then put a call through to your local HVAC contractor to have the problem fixed. Our experts are on hand to take care of every of your maintenance and repair needs. Call us today!