Window Unit Freezes up


If you live in an area where it frequently drops below freezing, your window air conditioner will freeze because they are not made to operate in extremely cold conditions. It’s normal for this to occur when the device is operating or when it’s not being used properly.

Keep on reading to learn more about how to prevent your air conditioner from freezing up.

How do I stop my window air conditioner from freezing up?

Mechanical issues, insufficient refrigerant, and insufficient airflow are the three main causes of window air conditioners freezing up. Pressure and temperature might fall as a result of mechanical component failure. These problems may result in condensation building up on the coils, which could subsequently freeze.

This problem can also be brought on by lowering an air conditioner’s temperature too much, but this is a user mistake. Before doing the necessary maintenance, turn up the temperature on your air conditioner.

The evaporator coils being covered in ice is the most visible indication when a window air conditioner is frozen. As soon as you realize a problem, you need to start solving it. Unless the damage is extremely severe, fixing it can be a do-it-yourself project.

Learning how to keep a window air conditioner from freezing up in the first place is the best method to avoid this from happening. Regular maintenance and repair of the unit are crucial and can end up saving you a ton of money.

Cleaning the Evaporator Coils

Evaporator coils need to be kept clean if you want to avoid air conditioner freeze-ups. You will need a 4-in-1 screwdriver, an air conditioner fin tool, rags, a shop vacuum, and leather work gloves to complete this routine maintenance on your window A/C unit. Additionally, acquire some all-purpose household cleaners, an electric motor oil bottle, some A/C coil cleaning, and a nylon bristle brush. To keep the evaporator coil from freezing, it must receive a sufficient flow of hot air.

Snap the plastic trim panel/filter holder off and unplug the device. Then, enlist the aid of a friend to remove the device from your window or wall. Use the screwdriver to remove the mounting frame or casing for window units. Use the fin comb to straighten any bent fins while wearing the gloves. After cleaning the coils of any dust and debris, spray both coils with coil cleaner. Heavy buildup can be removed with the brush by brushing in the direction of the fins.

Why does my window ac unit air conditioner keep freezing over?

Here are the main causes of a window air conditioner freezing and, when possible, how to fix the issues without having to buy a new unit or take it to a professional for repair.

The Outdoor Temperature is Too Cool

The entire system will operate at a temperature that might soon cause the evaporator coil and the window air conditioners freeze if the outside air is too cold. If the outside temperature is below 60 degrees Fahrenheit, avoid using your air conditioning. Open a window or two if you need cooler air in the house at that time rather than trying to utilize your window air conditioner to cool it.

A Refrigerant Leak

If your window air conditioner’s coils and air filter are clean and in good shape but the machine still won’t cool, this could be the cause.

A window air conditioner’s refrigerant is contained in a closed system and ought to last the duration of the appliance. It should never be “spent up” or leaked through the system. The device won’t operate as it should if there is a leak, and freezing up could be one indicator of this.

A qualified HVAC expert must handle a refrigerant leak because it is a serious issue. Many states only permit someone with a certain license to handle refrigerants. The best course of action may be to think about replacing your window AC with a newer model if it has a refrigerant leak because your unit is likely at least ten years old. For an estimate of the price to fix a refrigerant leak, speak with your HVAC technician. You’ll probably find that the unit isn’t worth repairing.

Poor Airflow – Dirty Air Filter

The most common reason for a frozen window AC unit is a dirty filter. Pet hair and common airborne dust and debris are the main culprits for clogging filters. This could lead to a frozen evaporator and restrict airflow in regular circulation through the air conditioner. This reason could also prevent the AC unit from working properly. Regular air filter cleaning will stop this from occurring. Observe the directions in the user manual that was included with your device.

If this is the issue, you can simply check. Pull the filter out. If so, adjust the AC to the maximum cooling setting, like Hi Cool. For a few minutes, let it run. Have you heard the compressor start to operate? Is it getting colder already? You should be in good shape if you clean that filter.

Poor Airflow – Dirty Components 

In addition to passing through the filter, the air must also pass through the evaporator’s front fins and then the condenser’s back fins. The distance between these tiny fins is quite small. They are prone to clogging up with dust and pet hair, making the entire device difficult to circulate air through. If the fins are dirty, carefully clean them with a soft cloth, a brush, or compressed air. Be careful not to flatten or bend them, as doing so will lessen their effectiveness.

Broken or Loose Fan

Your window air conditioner’s blower fan is what keeps the air flowing through it. The air won’t move as it should if the blades are broken. The fan won’t be spinning at the right speed if it is hanging loosely on its shaft. A broken fan blade needs to be changed. A tiny set screw on the fan’s collar can be tightened to secure a loose fan. Additionally, check the fan for any extra dust or dirt.

Damaged Component

A window AC has several internal parts that can break down over time, leading to the formation of ice on the evaporator while the machine is still operating. The temperature sensor, electronic control board, run-start capacitor, blower fan motor, and others are a few of these components. A licensed HVAC technician would probably be best able to diagnose all of these issues.

What can I do if my AC unit freezes up?

Before attempting to solve the issue, it is important to determine the problem’s primary source because there are numerous other potential reasons. You may either clean or change the filter if it’s dirty. You can use a vacuum cleaner to clean the coil if it is clogged. You can increase the refrigerant level if it’s low. You might have to replace the complete appliance if none of these fixes succeed.


A window air conditioner unit should work effectively for 10 years or longer with regular care and maintenance. By the manufacturer’s instructions, install and maintain it. This entails routine filter maintenance as well as removing the cover to clean the coil fins and internal parts at least once each season.

Plan to thoroughly clean your window AC twice per season if you use it from spring until well into the fall.

Maintaining your air conditioner will allow you to enjoy cool, comfortable air in your space while preventing the issue of a frozen window air conditioner.