Why is My Window AC Unit Freezing Up and How to Fix It

Are you tired of experiencing the frustration of a window ac unit freezing up? Well, you’re not alone! 

I have personally faced this issue, and I can understand the inconvenience it can cause. 

That’s why I’m here to share my experiences with you, so you can effectively deal with frozen window air conditioners.

In this article, we’ll dive deep into the causes of window air conditioners freezing up and explore practical solutions to deal with it. So, let’s jump right in!

Signs of a Freezing Window Air Conditioner

Here are some signs that indicate your window air conditioner may be freezing up:

• Weak airflow: If the air coming out of your AC feels weaker than usual, it could be a sign of freezing. This happens when ice builds up on the coils and restricts the airflow.
• Poor cooling: If your AC is struggling to cool the room properly, it might be freezing up. You might feel like the air isn’t as cold as it should be or that the room temperature remains high even when the unit is running at high settings.
• Ice or frost: If you see ice or frost on your AC unit, it’s a clear sign of freezing. You might notice ice on the coils, vents, or even on the outside of the unit.
• Water leaks: Freezing can cause ice dams to form, leading to water leakage. If you see water pooling around or dripping from your AC, it could be a result of freezing up your window AC unit.
• Strange noises: A freezing AC can produce unusual sounds like bubbling or hissing. These noises occur when refrigerant moves through partially frozen coils.

Learn: Why does my window ac making a loud noise?

If you notice any of these signs, it’s important to take action. Turn off your AC, let it thaw, and check for possible causes and fix anything wrong.

What to do when your window ac unit freezes up?

When your window air conditioning unit freezes up, the first thing you have to do is to try to thaw it. This is super important and you should not ignore it. 

To thaw your unit, start by turning off the unit to prevent any further damage and just leave as it is for some time for the ice to thaw.

Depending on how much ice has built up, it may take a few hours or longer. In some cases, it may take up to 24 hours. But you can speed up the process by:

• Removing any visible ice or frost from the unit using a soft cloth or towel.
• Increasing the airflow by opening doors and windows in the room. 
• You can also use fans to circulate air around the air conditioner and help with the thawing process.

Learn: How to thaw your frozen ac faster?

Why does my window AC freeze up?

Based on my personal experience, I have identified 7 causes of window AC freezing up. Here they are:

1. Insufficient Airflow:

Insufficient airflow is the most common cause of window air conditioners freezing up. When the air doesn’t flow properly, the evaporator coil becomes colder than necessary, which leads to condensation formation. Instead of draining, the condensation freezes on the coil’s surface, gradually forming ice.

This ice buildup further restricts airflow, reducing the cooling capacity of the AC unit. It can occur due to various factors, such as:

• Dirty Air Filters: When air filters become clogged with dust and debris, they restrict the airflow passing through the unit. As a result, the evaporator coil doesn’t receive enough warm air which leads your window ac to ice up.
• Blocked Vents: If vents are blocked or closed, air can’t circulate properly. The restricted airflow limits the heat exchange process and can cause the evaporator coil to become excessively cold, leading to freeze up your ac unit.
• Obstructions near the Unit: Placing furniture or other objects near the window air conditioner can obstruct the airflow. These obstructions disrupt the air circulation and prevent the proper functioning of the unit, which can potentially result in freezing.

2. Low Refrigerant Levels:

Low refrigerant levels can contribute to window air conditioners freezing up. Insufficient refrigerant leads to inadequate heat absorption and inefficient heat transfer in the AC system.

As a result, the evaporator coil doesn’t cool the air effectively, causing moisture to condense and freeze. Some possible causes of low refrigerant levels could be:

• Refrigerant Leaks: It is the most common cause of it. Over time, leaks can occur in the refrigerant lines of the ac unit. 
• Improper Installation or Charging: If the air conditioner was not properly charged with refrigerant during installation or maintenance, it can lead to low refrigerant levels.

3. Faulty Thermostat:

A faulty thermostat can cause your window ac to freeze up. Think of the thermostat as the brain of your air conditioner. Its job is to regulate the cooling process based on the desired temperature you set. 

However, if the thermostat is faulty, it may get confused and may keep signaling the AC to cool even when it’s already cold enough. This constant cooling causes ice to accumulate on the evaporator coil of your window air conditioner.

4. Malfunctioning fan or motor

A malfunctioning fan or motor in a window AC  unit can also cause it to freeze up. The fan and motor work together to keep the air flowing and remove heat from the AC. 

However, if the fan is broken or loose and isn’t doing its job properly, it won’t be able to bring in enough air or circulate it well. This means there won’t be enough air passing over the cooling coils.

Without enough air, those coils can’t transfer heat properly. As a result, they get too cold and any moisture in the air can freeze on them, creating ice.

And if the motor is not working the motor is not working it can further disrupt the airflow.

5. Dirty Evaporator Coils

Did you know that dirty evaporator coils can be the main reason why your window air conditioner freezes up? It’s true! 

When the coils get covered in dirt, they fail to do their job properly. These coils struggle to absorb heat and cool the air, which causes them to become too cold and freeze.

But that’s not all. The dirt on the coils also blocks the airflow, making it harder for the heat exchange process to work correctly. This makes the coils even colder and more likely to freeze.

So, if you neglect to clean your window air conditioner dirty evaporator coils, you’re inviting freezing problems.

Troubleshooting Tips for a Frozen Window Air Conditioner

To resolve a frozen window air conditioner, follow these troubleshooting tips:

1. Check the Air Filter

Start by inspecting the air filter and make sure it is clean and clear from dust and dust.. A clogged air filter restricts airflow, leading to freezing. If the filter is too dirty, replace it with a new one.

2. Clean the Evaporator Coils

Next, clean the evaporator coils to remove dirt and debris. Turn off the air conditioner and gently clean the coils using a soft brush or vacuum cleaner. Keep in mind to clear out all the dirt that has accumulated on the coil. Avoid using excessive force to prevent damage.

Learn: How to Clean a Window AC Evaporator Coils?

3. Ensure Proper Airflow

Check that all vents and air ducts are open and unobstructed. Clear any obstructions such as furniture or drapes that might hinder proper airflow around the unit.

4. Check and maintain Refrigerant Levels

Maintaining proper refrigerant levels is crucial to prevent your window air conditioner from freezing up. The refrigerant is basically a substance responsible for absorbing heat from the indoor air and releasing it outside, allowing the cooling process to take place.

If the refrigerant levels are too low, it can lead to various issues, which includes freezing of the unit.

Check the refrigerant level and if you suspect low refrigerant levels, it’s best to seek professional assistance. A qualified technician can inspect and recharge the refrigerant as needed.

5. Inspect the Thermostat

Well, as I mentioned earlier, the thermostat is like the brain of your air conditioner. If it fails, it can cause your window ac unit to ice up. So check the thermostat settings and make sure they are accurate.

To check it, set it to the desired level and in the right mode, like cool or auto. If the settings seem fine, you’ll want to check if it’s accurately sensing the room temperature. 

If you suspect a sensor problem, it’s best to get a technician involved. They can check the sensor and make any necessary repairs or replacements. 

Sometimes, the thermostat can also have electrical issues, like loose connections or wiring problems, so keep in mind to look out for those too.

6. Check the Fan Motor

The fan motor job is to circulate the air throughout the air conditioner and expels heat. It works hand in hand with the fan to keep things moving. If it isn’t working, it can lead to freezing, poor cooling performance and can also make your window ac noisy.

Learn: Why does my window ac sound like running water?

To check the fan motor, turn off the air conditioner and access the unit. Then, look for any visible signs of damage or wear, such as frayed wires or loose connections. Also, listen for any unusual noises when the unit is running, as this could indicate motor problems.

BTW, if you find any loose connections, gently tighten or reconnect them using the appropriate tools, such as a screwdriver or pliers.

If you notice frayed or damaged wires, replace them. Cut out the damaged section of the wire using wire cutters and strip the ends to expose fresh, clean wire. Connect the new section of wire using wire connectors or electrical tape.

However, if you find any major issue with the motor that you think you can’t fix then it will be best to get help from an expert.

7. Clear Obstructions around the Unit

When objects like furniture, curtains, or plants block the airflow around your AC unit, it can disrupt the cooling process. Adequate airflow is crucial for the air conditioner to work efficiently and prevent overheating.

So, it will be more beneficial for your unit if you clear any obstructions around it. Ensure that curtains or blinds are not covering the vents of the air conditioner. Improper ventilation may also cause your window ac to smell like fish. If you have plants or shrubs near the air conditioner, make sure they are trimmed.

Ensure a minimum of two feet of clearance around the unit, which is enough for optimal airflow and heat dissipation.

What are some preventive measures to avoid future freezing in window air conditioners?

So if you want to prevent your window air conditioner from freezing up in the future, adopt these preventive measures:

1. Clean and maintain the air conditioner regularly: Regular cleaning the unit and removing any debris or dust that accumulates on the coils or vents is important for overall performance of your unit as well prevent it from icing up.
2. Ensure proper airflow around the unit: Keep the area around the air conditioner free from obstructions. Avoid placing objects near the vents, clean the air filter on a regular basis and check that the vents are not closed or blocked to ensure proper airflow.
3. Maintain adequate refrigerant levels: Regularly check the refrigerant levels and top up if necessary. Low refrigerant levels can lead to icing and decrease cooling efficiency of your unit.
4. Check and calibrate the thermostat: Periodically inspect the thermostat to ensure it is functioning correctly. If you notice any issues, consider repairing or replacing it.
5. Seek professional help if needed: If your air conditioner continues to freeze up despite taking preventive measures, it’s advisable to contact a professional HVAC technician. They can diagnose the underlying problem and provide the necessary repairs.

Read: Top quality low sound level window ac of 2023

FAQs: Window Air Conditioner Freezing Up

Key Takeaway

A frozen window air conditioner can be a real headache. But don’t worry! But fear not! We’ve got your back with some handy tips. First, watch out for signs like ice buildup or reduced cooling.

If you spot them, here’s what to do: check for any blockages that might be messing with the airflow, and make sure the air filter and the evaporator is free from dirt and dust.

But hey, it’s not just about fixing the problem once it happens – you can actually prevent it from happening again! How? Well, by keeping up with regular maintenance, cleaning the filter, and giving your AC some room to breathe.

More on related to Window Air Conditioner:

• How to set up a window ac in vertical sliding window?
• How can I clean mold out of my window aircon?

David Jack

David Jack is a veteran when it comes to air conditioners, he love helping people find solutions to their problems with AC units. His specialty is helping people find the right Air-Conditioner for their needs, whether that means replacing a broken unit or adding on to an existing system. He is also great at diagnosing problems and fixing them quickly. He learned this from my father Jack Smith who was an air conditioner repairer, he has 2 years of experience in this field.