Air Conditioner Freezing Up: Causes and Solutions

If you’ve ever experienced your air conditioner freezing up, you know how uncomfortable, inconvenient, and frustrating it can be.

  • But what is the reason for the freezing of the air conditioner?
  • What to do if your air conditioner is already frozen?
  • And, how can you keep your air conditioner from freezing up?

All of these questions are covered in this post, so if you want to know more about air conditioner icing keep reading!

What causes the air conditioner to freeze up?

Here we’ll go over the common causes of a frozen air conditioner.

#1 Blocked or clogged air filter

One of the most common reasons why an air conditioner freeze up is a blocked or clogged air filter. When the filter becomes clogged with dust and debris, it restricts the airflow to the unit, which causes an accumulation of cold air inside the AC system. If the airflow is completely blocked, the evaporator coil gets too cold and freezes up. 

#2 Insufficient refrigerant levels

When an air conditioner’s refrigerant level is too low, unsurprisingly, it can make the air conditioning ice up. A refrigerant is a substance that takes heat from inside your home and transfers it to the outside of your home.

If there is a leak, or if the system was not charged properly initially, this can lead to low refrigerant levels, and result in the unit freezing up. 

#3 Blocked airflow

As I mentioned earlier, if the filter on your air conditioning unit is clogged, it blocks the airflow which can cause the evaporator coils of your air conditioning unit to freeze.

But what are the other causes of blocked airflow? Here are some more problems that may be blocking airflow from your unit. 

  • Obstructed air vents: Air vents can be blocked by various objects such as furniture and curtains, which can limit the flow of air to the air conditioning unit.
  • Leaky Ducts: If you are using a portable air conditioner or any AC unit that comes with a duct pipe, and if that duct pipe is leaking, it can reduce airflow.
  • Faulty Fan: A broken or malfunctioning fan can be another cause of restricted airflow.

#4 Blocked condensate drain line

As we all know, air conditioners work by circulating refrigerant through a system of coils to cool the air inside your home. As this air cools, it creates condensation which then needs to be removed from the unit.

And if the condensate drain line becomes blocked with dirt, dust, or other debris, it prevents condensation from draining from the unit. This eventually leads to the air conditioner freeze up.

#5 Compressor failure

The compressor is the grandmother of an air conditioner. This is the motor that pumps the coolant through the air conditioning unit, and if it fails, the coolant will not circulate, causing the coolant to get too cold and freeze. 

Signs of compressor failure include:

  • Loud noises coming from the unit
  • Fluctuating temperatures
  • Lack of cool air

#6 Dirty condenser coils

A common reason for an air conditioner freezing is dirty condenser coils. If you have been using air conditioners for a long time or even if you have little knowledge about air conditioners, you would already know that condenser coils are responsible for removing heat from the refrigerant.

When dust and debris accumulate on the coils, this prevents them from doing their job effectively, resulting in the icing of the air conditioner.

What to do if your air conditioner freezes up?

Here, we will discuss what to do if your air conditioner is frozen.

Step 1: Turn off the air conditioner

When you notice that your AC unit starts to freeze, the first step is to turn off the air conditioner. This will help prevent any further damage to the AC unit and prevent any possible icing. 

Step 2: Wait for the unit to thaw

Wait for it to thaw after turning off your AC. It may take some time for the ice on the unit to melt completely, don’t rush, give it enough time to melt. Also, don’t try to use a sharp object to break the ice off the coils. This may break the coil or cause some other damage.

Step 3: Let the coils dry properly

Then you need to dry the coils properly. Use a towel to wring out the water from the coil and leave it in the presence of sunlight for some time.

Step 4: Locate and clear any blockages

After that, you will need to locate any blockages that may be causing the AC unit to freeze and clear it. This may include blockages in the air filter, ducts, or other components. Check for dirt, debris and dust build-up as well as blockages caused by insects.

How do I stop my air conditioner from freezing up?

I can understand how frustrating it can be when your air conditioner freezes. I have personally experienced this problem with my unit. However, once I knew why my air conditioner unit was freezing, I was able to take action and get it resolved quickly.

I want to share with you some additional tips to help you prevent your air conditioner from freezing. Here, are the 9 ways to prevent your air conditioner from icing up

#1 Checking and replacing dirty air filters

Dirty filters can be the main cause of your air conditioner icing up. A dirty air filter can cause a number of problems with your AC system, including:

  • Increased energy costs
  • Stress on the motor and fan
  • Increased indoor air pollution, as the filter is not able to effectively remove pollutants from the air. 
  • Reduced airflow
  • Shortened lifespan

That’s why it’s important to check and clean dirty air filters from time to time.

To check your air filter, start by turning off the air conditioning unit, then pull out the air filter, which is usually located in the return air duct near the blower compartment. If the filter is dirty then clean it and if it is in very poor condition then I would recommend you replace it.

Cleaning the air filter

And as an HVAC expert, I recommend that you clean the filter every 30 days and replace it with a new one every 90 days, depending on your environment and usage. 

#2 Monitoring refrigerant levels

The refrigerant in your air conditioner is an essential component of the system, as it helps keep air flowing smoothly and evenly throughout your home. To prevent the air conditioner from freezing, you must regularly monitor the refrigerant level. 

And it is important to note that the right amount of refrigerant is present so that it can properly absorb the heat and properly circulate the cool air throughout the room. If you notice a leak or if the pressure in the system drops too low, you should call an HVAC technician immediately.

#3 Inspect your ductwork

This is an important task. When inspecting your ductwork, look for any holes or disconnected sections. This can reduce airflow, which can lead to uneven cooling and freeze up of the air conditioning unit.

If you notice these issues, follow the following steps to seal your air conditioner duct pipe:

  1. Locate the damaged area: Use a flashlight to inspect the ducts and locate any tears, holes, or disconnected sections.
  2. Clean the area: Use a stiff brush to remove any debris or dust from the area around the holes. This will help ensure a proper seal.
  3. Use metal tape or mastic: For small holes, use metal tape that is specifically designed for HVAC ducts. And use mastic sealant to seal large holes or cracks on the duct pipe.
  4. Apply the sealant: For metal tape, apply it to the holes taking care that it overlaps the duct by at least 2 inches on all sides. For mastic sealant, use a putty knife to apply it to the cracked area.
  5. Let it dry: Let the sealant dry for some time.
  6. Repeat the process if necessary: Repeat this same process again, if you find another hole or crack in your air conditioner duct.

#4 Check if all vents are open and not blocked

This is one of those big mamas that blocks or reduces airflow to your air conditioner. That’s why it’s important to make sure all vents are open and not blocked.

Blocked vents can reduce airflow to the air conditioner, which can lead to uneven cooling, hot spots in the home, and icing. If you notice any blocked vents, take the time to clear them so air can circulate freely. 

But understanding the causes of blocked vents is more important than opening them.

  • Dirty air filter
  • The ducts may be blocked by debris, insulation, or other materials.
  • Vents may be closed or blocked by furniture or curtains.
  • If the ducts are leaking, they can cause pressure imbalances, which can cause some vents to be blocked.
  • Clogging in the Drain Line of the AC can also cause blocked vents.

Now, here are the steps of fixing the blocked vents.

  1. Pinpoint the Air Filter: The first step in this process is to locate the air filter in your AC unit.
  2. Replace or clean the filter: If the filter has been used for more than three months, replace it. But if it looks a little dirty, just wash it with soap and water and let it air dry before reapplying.
  3. Inspect the ductwork: Look for any obstructions in the ductwork, such as debris or insulation. Use a vacuum cleaner to remove any debris.
  4. Check the vents: Make sure all vents are open and free of any furniture, curtains and other items that could be blocking them.
  5. Check for leaks in ducts: Check for leaks in ducts, such as gaps or holes. If there are gaps, seal them using mastic or metal-backed tape, or you can also consider hiring a professional to fix them.
  6. Drain Line Cleaning: If the above steps do not solve your problem, then the problem could be with the clogged drain line of the AC. It can be cleaned with a stiff wire or vacuum.

After resolving these issues, turn on the air conditioner and test to see if the blocked vents are resolved. If it is still not resolved, call a professional to inspect and diagnose the problem.

#5 Check and adjust the thermostat settings

This is one of the easiest ways to prevent your air conditioner from freezing up is to check and adjust your thermostat settings.  The ideal temperature range for your home should be between 70 and 78 degrees. Ensure to adjust the thermostat to the proper temperature. 

If the temperature setting is too low, it can cause the air conditioner to work harder than necessary and potentially cause a freeze-up. Also, if you can, I recommend considering getting a programmable thermostat if you have an older unit; It will save energy and money by setting the temperature according to the time you are at home or out.

#6 Check the fan blades and motor regularly

To prevent your air conditioner from freezing, it is important to regularly check your air conditioner fan blades and motor for wear and tear as a bad fan or motor can be the main cause of your air conditioner freezing.

Some signs of a damaged fan or motor in an air conditioner include:

  • Loud or unusual noises coming from the unit
  • The fan is not running or is running slowly
  • The unit is not blowing air or is blowing weakly
  • The AC is not cooling the room properly
  • The circuit breaker keeps tripping when turning on the AC.

The fan blades need to be in good working order so that the unit can operate efficiently and effectively. If you find that the fan blades are damaged or worn, you should replace them immediately. 

However, the above signs may also indicate other problems with the air conditioner such as:

  • A problem with the belts
  • A clogged air filter
  • A malfunctioning thermostat

Therefore it would be best to have a professional HVAC technician inspect the unit to determine the cause of the problem and make any necessary repairs.

#7 Regularly clean the evaporator coils

As we talked about earlier, the evaporator coil of your air conditioner is responsible for absorbing heat from the air. But when these coils get dirty, they don’t absorb heat as efficiently and can cause the system to freeze up. This can be prevented by regular cleaning of the evaporator coils.

Steps for Cleaning the Evaporator Coils:

  1. Locate the access panel for the evaporator coil and remove the cover to continue with the process.
  2. Use a vacuum cleaner, and remove any dirt and debris from the coils. But keep in mind that the fins should not be bent or broken while cleaning. If it breaks then there will be a big problem.
  3. After you finished cleaning, check the fins to ensure they are straight and are not damaged.
  4. If any fins are bent, use a fin comb to make them straight.
  5. After completing these above steps, re-place the access panel and secure it.

Finally, put the cover back on and turn your air conditioner back on. 

#8 Keep the area around the air conditioner clear of debris and foliage.

Cleaning the area around the air conditioner is super important. Debris and leaves can reduce airflow and reduce the efficiency of your air conditioner, as well as cause it to freeze. Leaves, sticks, and other items can get inside your unit and damage the fan blades or motor, causing even more problems. 

So remove any dust, sticks, debris or leaves from around your air conditioning unit. It’s best to do this at least once a month during the summer, when you’re using your unit all day long.

If you have plants near your air conditioning unit, make sure they are trimmed back to prevent any obstruction.

#9 Schedule Regular Maintenance

How to Maintain an Air Conditioner

Last but not the least you should schedule regular maintenance of your AC unit. If you are a regular reader of this blog, then you know that I have mentioned this many times before, that you should maintain your air conditioning unit at least once a year.

Maintaining and cleaning your air conditioner is the all-in-one solution for your air conditioner. These are many advantages of regular maintenance. You should call an HVAC technician to tune-up your unit.

Maintenance include:

  • Cleaning or replacing air filters
  • Checking and cleaning ducts
  • Inspecting and tightening electrical connections
  • Lubricating moving parts
  • Checking the system’s refrigerant levels
  • Checking for leaks or damage to the system
  • Making necessary repairs or adjustments to ensure optimal performance
  • Inspecting and maintaining the outdoor unit
  • checking the thermostat and its calibration

Well if you are sure that you can handle the maintenance of your AC unit yourself, click here to check out our complete guide to AC unit maintenance.

FAQ: Air Conditioner Freezing Up

In this Frequently Asked Questions (FAQ) section, we aim to provide comprehensive answers to some of the most common questions regarding air conditioner icing, so that you can gain a deeper understanding of the issue.

Q1: How long does it take to unfreeze an air conditioner?

Ans: The amount of time it takes for an air conditioner to freeze can vary depending on the severity of the freeze-up. In general, it should take about an hour for the ice to melt. However, if the freeze-up is more severe and affects multiple coils, it may take more than an hour to unfreeze.

Q2: Can a dirty filter cause AC to freeze?

Ans: Yes, AC can freeze due to dirty filters. Because a clogged filter restricts air flow. This causes the evaporator coil to be unable to absorb enough heat and the refrigerant flowing through it becomes too cold, eventually freezing it.

Q3: What is the best way to thaw a frozen air conditioner?

Ans: The best way to thaw a frozen air conditioner is to turn off the power and let the unit thaw on its own. It may take an hour or more to melt completely. To speed up the process, you can try turning on a fan in the room and circulating the air around the coils.

Q4: Why is the outside air conditioner unit freezing up?

Ans: There are many reasons for the outside air conditioner unit to freeze up, but the most common reason is lack of maintenance. This can cause dirt and debris to build up on the evaporator coils, leads to reduced airflow and causes the coils to freeze up. Other causes include a low refrigerant level, a clogged condensate drain line, or a bad blower fan motor.

Wrap Up: What causes an air conditioner to freeze up?

We hope this blog post has provided you with the information you need to keep your air conditioner from freezing this summer. By understanding the causes of air conditioner freeze-ups and taking the preventive steps I’ve outlined above, you can prevent your air conditioner unit from freezing in the future

If your air conditioner is already frozen, don’t panic! Try some of the solutions listed in the post, or contact a professional if necessary. With the right approach, you can have your air conditioner back running in no time.

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David Jack

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.

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