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What Does It Mean When Your Air Conditioner Freezes Up?


One of the common issues you’ll face when owning an air conditioning unit is finding its entire HVAC system freezing. You’d assume that freezing is excellent for an AC and will create cool indoor air, but unfortunately, that’s not the case. Due to how an air conditioner unit works, the evaporator coil and HVAC system that generates cold air might freeze without actually cooling your air.

A frozen AC unit or AC system will either blow warm air or nothing at all, and this can be quite a hassle, particularly during hot days when a cool air flow is badly needed. So, what does it mean when your air conditioner freezes up? Read below to know the reason why your AC freezes and the steps you need to follow to fix it.

Is It Normal for an Air Conditioning Unit to Freeze Up?

Before we go into the causes of a frozen AC, let’s go over how your air conditioning system works. The purpose of an air conditioner is to chill the refrigerant inside the evaporator coil. The cooling coils or indoor coil removes the heat so that when enough warm air is sucked up and exits the air conditioner, it cools the space inside your home and efficiently eliminates the hot air.

However, if something in the AC unit fails, the evaporator coil over-cools the refrigerant, causing it to drop below freezing and have ice forming in the AC compressor. This process doesn’t normally happen overnight and can be caused by several factors such as infrequent HVAC maintenance, insufficient airflow, and others.

Reasons for Air Conditioner Freezing

Whether it’s blowing cooled or heated air, your air conditioner accumulates excess moisture in its condensate lines, coils, and other parts. These excess water freezes and condenses on these components and when the ice forms, you may discover that your air conditioner only blows warm air. 

Below are the major causes of AC freezing, and knowing how to avoid these causes can help you save money in terms of AC repairs.

Ventilation/ Clogged Air Filter

Lack of ventilation is probably the most common cause of air conditioner malfunctions. This can be caused by a variety of issues ranging from dirty evaporator coils to clogged air filters. Adequate airflow is important for an AC to function at its peak performance, and if anything in the airflow system prevents warm air from passing through refrigerant lines while the compressor continues to operate, your air conditioner will begin to freeze. If left unattended, the problem will only worsen over time.

A clogged air filter is possibly the easiest problem to solve, but it is also the most overlooked. Since the dirty air filter itself is too dusty to actually filter anything, it registers/ prevents adequate airflow. Not using an air filter is also an issue, since AC refrigerants are frequently wet as a result of moist air condensing on the cool surface of the HVAC coils. When dusty air blows over these moist coils, it forms a dense blanket. That dust works as an insulator, trapping the cold inside the coils themselves, resulting in an extremely cold refrigerant. This, along with increased moisture on the dust, might result in frozen evaporator coils.

Low Refrigerant

The second most common reason for air conditioners freezing lies with the AC’s cold refrigerant. Because of how your AC maintains pressure, the quantity of refrigerant inside your coils plays a huge part in maintaining the AC’s cooling capacity. The outdoor AC unit or compressor compresses the refrigerant after releasing the heat it has collected. Warm air turns this liquid refrigerant into a gas, which warms up and causes pressure inside the AC to decrease. The compressor then compresses it back into a liquid and pushes it back towards its fan motor or blower fan.

If there are low refrigerant levels in the AC, this process happens too early owing to a lack of pressure. The AC then generates enough cold in that second to condense moisture onto the outdoor coil, quickly freezing it. As ice accumulates, it fills the AC or outdoor unit and climbs up the copper pipes. This is why maintaining adequate refrigerant levels in your AC system is a critical step in preventing a frozen AC or a frozen HVAC system.

By recognizing these reasons and taking steps to ensure your AC is well-maintained, you’ll never have to deal with your air conditioner freezing and causing you headaches again.

What Do I Do if My AC is Frozen?

What Does It Mean When Your Air Conditioner Freezes Up?

If your unit has frozen HVAC coils, there are several easy actions you may do to get your AC back up and running. The first thing you should remember is to turn off the AC while thawing out the frozen coils strains, since running the air conditioner with frozen coils puts a burden on the compressor. Go to the circuit breaker or electrical breaker and turn off the electricity if needed. 

Additionally, don’t break up the ice with a sharp tool, like a knife or a blunt tool. This quickly destroys components that circulate air, to the point where you’ll need to replace many parts. Worst-case scenario, you’ll be forced to replace the system entirely, which is definitely costly.

Let the ice thaw, and once melted, you can dry the evaporator coils. You can use paper towels or let the components dry in the sun if it’s an outdoor unit and they are in direct sunlight.

Afterward, identify which problem caused the AC to freeze up. These issues include:

Blocked or Poor Airflow

Pulling heat from a room requires a steady flow of air to prevent the air conditioner from freezing. A clogged filter or dirty coils can disrupt proper airflow so it’s important to clean evaporator coils or AC filters every week or so. Air filters are inexpensive and are important to keep the air circulated by your AC clean, so it is recommended to replace them on a regular basis. In short, keep your air conditioner clean and tuned up to avoid airflow issues.


Aside from the unit itself, your environment can also cause your air conditioner to freeze. Air conditioners are programmed to function within a set of ideal temperature thresholds. When summer evenings are cooler than the ideal threshold ACs are built for, it might throw the unit’s entire HVAC system out of sync.

A programmed thermostat can automatically solve the problem. It is programmed to turn off the air conditioner when temperatures fall below 60 degrees. If your unit doesn’t have a programmed thermometer, you’ll have to monitor the current temps each night and switch off your AC when the temperature might reach below 60 degrees.

Refrigerant Issues

Another thing that causes your air conditioner to freeze is mechanical issues, like a coolant leak. If you think your AC has more serious problems than the two previously mentioned issues, it’s better to call in an HVAC professional who specializes in these types of repairs. Though refrigerants are safe to use in the house, it’s crucial you avoid handling coolant chemicals. Regular tune-ups by an HVAC specialist are recommended to help prevent catastrophic difficulties with your AC.

Once all the issues are fixed, reconnect your system’s electricity and adjust it to only run the blower or fan. Your AC unit should be fit to use once the coils have properly dried.


A frozen air conditioning unit is a common and aggravating problem for homeowners that simply want to enjoy a comforting space to relax. However, the problems that cause a frozen air conditioner may be avoided with regular maintenance.  Keeping your unit in good condition not only keeps your home cool, but will also help you save money on your energy bill and maintain your unit’s optimum performance.

Need to buy an aircon or simply want to know how to keep your current one in good shape? Take a look at some of our aircon reviews and aircon-related articles on this site.

Frequently Asked Questions

How do you unfreeze an air conditioner fast?

With your AC freezing, merely turning off the air conditioner will not melt the ice quickly enough. However, this process can be accelerated by applying heat to the ice.

Hold a blow dryer at least 10 inches away from the evaporator coils to heat up the ice. Don’t raise the temperature or get any closer than 10 inches away since the heat might damage the evaporator coils.

When all of the ice has melted, switch the air conditioner to ‘fan only’ mode. The fan will circulate heated air within the air conditioner, drying it out completely. Keep the AC in fan-only mode until all remaining ice has melted and the extra moisture has evaporated.

When the unit is completely dry, go in and clean the evaporator coils. Remove any remaining adhering moisture, dirt, and debris with a soft cloth.

Note: Do not chip the ice using any blunt or sharp object. Additionally, make sure to clean the drain line and drain pan as well, since a blockage might cause an overflow. This in turn might damage the AC components or cause another freezing.

JP Reyes

JP has been in the aircon industry for almost as long as he has been alive. As a child JP would help his tatay fix aircon units at their junk shop in Cavite. After graduating UP in the early 2000's, JP then started his own Aircon servicing business and within 5 years had 10 shops in 8 different cities. Fast forward to today and JP brings all his experience and expertise online to give readers trustworthy advice and reviews about Air-conditioning buying, servicing, cleaning and repair in the Philippines.

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