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Why Does My Air Conditioner Freeze Up?

Whether you have an expensive
HVAC system or a simple window air conditioner, ice often develops on the evaporator coils. 


At first glance, this doesn’t make sense. When it’s 90 degrees outside, ice should be at the very bottom of your list of concerns. Still, this sort of thing happens, and it will leave you wondering why my air conditioner freezes up. 


Continue reading this article and it will all make sense by the time you get to the end.

Why Do Air Conditioners Freeze?

When it comes to ice formation on the internal components of an AC, it’s got everything to do with how most units operate. 


An air conditioner removes the heat and humidity from the air and moves it outside. For this to happen, various components need to work like a well-oiled machine. For example, a chemical referred to as refrigerant courses between the exterior and interior units in a closed-loop system. As it travels through the system, it absorbs and releases heat.


As the return vent sucks in indoor air, it hits the evaporator coil where the refrigerant “soaks up” both the heat and the humidity. It then transforms into a gas and travels to the compressor in the exterior unit. The compressor basically squeezes the refrigerant, increasing its temperature. Once the refrigerant moves to the condenser, the heat is expelled outside via the fan.


Next, the refrigerant cools down, changes back into a liquid state, and finally travels back into the indoor unit, repeating the entire process until your home cools down. 


Anything that impedes this finely-tuned process will throw off not only the performance of the entire unit but may lead to ice formation. For instance, if the airflow in the system is poor, not enough hot air will reach the evaporator coil, decreasing its temperature exponentially. As a result, insufficient levels of refrigerant will turn into gas, and the excess condensation on the coil may freeze up. 


A similar thing can occur if a refrigerant leak develops in the system. The evaporator will be too cold and it’s only a matter of time before it freezes. 


You may also wonder why my window air conditioner freezes up. The answer is the same. Window air conditioning units are significantly smaller than regular ACs, but they still have pretty much the same components. So, all the same rules apply to them as well. 

Common Problems That Lead to AC Freezing-Ups

In case you’re wondering why does my air conditioner freezes up and looking for specific issues, we’ve got you covered. Here are the main reasons why ice-related difficulties take place:

  1. Dirty filter

When the indoor air enters the system, it passes through an
air filter. However, the air filter will eventually get dirty and if it’s not swapped out regularly, it may impede the airflow in the system, leading to ice buildup on the internal components of the AC. 


You should change the filter every two months to ensure maximum airflow. The only exception to this are larger homes with pets, where it’s better to replace the filter once a month. 

 2.
Blocked Air Vents

Anything that puts your airflow out of balance may contribute to a frozen air conditioner, which means blocked return or take-up vents can also cause this issue. Plenty of homeowners unknowingly block these vents with household items or furniture, and some even close them believing doing so might help save energy. 

 3.
Dirty Evaporator Coil

Dust and debris may also end up in the evaporator coil and over time, the coil may get so dirty that the heat won’t be able to transfer properly. This often leads to ice formation, or in the worst-case scenario, the development of bio-growth. 

 4.
Clogged Drain Line

As we mentioned before, your AC also absorbs moisture from the indoor air. This results in condensation that drips into a drip pan and is drained out of the system via a condensate drain line. 


If this line becomes clogged, the water will accumulate in the system, which may either freeze or start leaking out of your unit. 

 5. Broken Blower Fan

This fan has an important role in the cooling system as it pushes the air across the coil. If it malfunctions, not enough air will reach the coils (and you know where this is going). In some cases, the fan will give out completely and your air conditioner will suffer a total breakdown as a result.

 6. Refrigerant Leak

When you ask the question why does my air conditioner freeze up, pray to a higher being it’s not

happening due to a refrigerant leak. A leak can materialize anywhere in the system, meaning it’s very tricky to diagnose. Plus, it will also lead to frozen evaporator coils, so if you don’t resolve the underlying leak, other components in the system may fail, such as the compressor. 


If you believe you have a refrigerant leak, you should call a technician immediately. 

Can You Get Rid Of The Ice On Your Own?

While you may not be able to fix a refrigerant leak or a blower fan yourself, you can perform a few actions for simpler stuff.


First, you need to replace the filter to restore the airflow and do a quick scan to make certain all vents are open. Then, check if the drain line is clogged. In case everything is kosher, switch the AC to fan mode – this allows the hot air to blow freely across the evaporator coils. In a few hours, the ice should thaw. 


Afterward, switch your AC back to auto mode. Keep a close eye on the unit for a few hours. If the ice forms again, you probably have a refrigerant leak or trouble with the blower fan, both of which necessitate assistance from a certified HVAC technician. 

Restore Your AC To Its Original State

The easiest way to make the problem go away for good is to reach out to
Mid-Fla Heating & Air. As the best technicians in Central Florida, we’re familiar with all the difficulties you’re facing because we’ve been there and we’ve done that. 


Along with 24/7 emergency services, we also have affordable maintenance plans that will help you immensely. All of the other issues listed above are preventable, so a tune-up and an inspection from our professional will eliminate the possibility of them taking place ever again. 


Ready to get started? Ring us at

561-750-1625 or fill out
our contact form.

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