How Do I Keep My Air Conditioner From Freezing Up?

A frozen air conditioner isn’t an uncommon sight in cold climates. In fact, you’d be very lucky to go through the AC’s entire lifespan without running into frozen coils at one point.  

Unfortunately, a frozen AC unit is bad news. It can leave with costly damages, including damages to the conder coils. Even the refrigerant lines may be affected. Moreover, a frozen AC unit can easily result in refrigerant leaks, exposing your and your loved ones to significant risk.  

This guide answers the most common questions about frozen air conditioners, focusing on how to prevent ac freezing. First though;

How Do I Keep My Air Conditioner from Freezing ?

You can take several steps to prevent ac unit freezing. These include maintaining the appropriate refrigerant levels at all times, changing the air filters regularly as the manufacturer recommends, and ensuring sufficient airflow through the air conditioner both inside and outside the house.

How Air Conditioners Work

To better understand how ac freezing happens, what causes it, and how to prevent and fix it, you need first to understand how air conditioners work.

Air conditioners are electrical appliances that extract heat from indoor air and dispose of it outside the house to lower indoor temperatures. They do so with the help of refrigerant, a special fluid that readily absorbs heat.

A typical air conditioner comprises an indoor unit, an outdoor unit, and connecting refrigerant and electrical lines. However, some units, such as window air conditioners, pack all three components into one unit. This guide focuses on mini-split units with separate indoor and outdoor units because these are the most cost-effective and popular today.

Mini-split air conditioners work in five distinct steps. It all begins at your thermostat. When temperatures rise above your thermostat setting, typically 75°F to 78°F, the thermostat signals the air conditioner to initiate the cooling process.

  1. The fan inside the air conditioner’s indoor air handler is powered and begins to rotate, drawing the warm air inside your house into the AC.
  2. The warm air flows over cold evaporator coil inside the air handler. The evaporator coil contain very cold freon. The refrigerant absorbs the heat as the warm air flows over the coils, leaving the air cold.
  3. The cold air is cycled back into your room via the indoor air handler. This is also known as return air.  
  4. Meanwhile, the now-warm refrigerant flows through the wall into the outdoor unit. The outdoor unit has two purposes. First, it has a condenser to “squeeze” out heat from the warm refrigerant. Additionally, it has a compressor to convert the refrigerant back to liquid.
  5. The liquid refrigerant then flows back into the house to collect more heat, and the process continues until your indoor temperatures drop to the thermostat level. At this point, the thermostat asks the AC unit to suspend cooling until the next request.  

What’s a Frozen AC?

Unfortunately, when the refrigerant inside the air conditioning system falls below 32°F, the moisture inside the air conditioner may freeze. When this happens, we say you have a frozen AC.

A frozen air conditioner means that the air conditioner now has ice blocks encasing the condenser coils.

what cause air conditioner to freeze up

How to Tell If your Air Conditioner is Frozen?

It’s easy to tell when you have a frozen air conditioner. The following are five telltale signs to keep an eye out for;

  • The air conditioner produces warm air: Although the AC unit can blow warm air for many reasons, frozen evaporator coils are one of the most common reasons. This usually happens because the AC unit no longer extracts heat from indoor air. So, the air returns to your home still warm.
  • The air conditioner produces no air at all: In extreme cases, the airways through the AC unit can become blocked, meaning you may not get any air at the return vents at all. Alternatively, you may get a very weak stream of not-so-cool air.
  • You can see ice on the outside unit: You never want to get to this point. Nevertheless, if you see ice on the outside unit, there’s likely freeing inside the AC. The freezing is usually so bad inside that the effects have spread outside the unit by this time.
  • The copper coils inside are covered in ice: You need to open the access panel to view the coils. The access panel is located in different locations depending on the AC model. Nevertheless, if the condenser coils are covered in ice, that’s another sign of trouble.
  • Visible extra condensation: Besides ice, you may also notice condensation or pooling water around the outdoor unit. This is also often a sign of ongoing freezing. The bigger the water pooling, the bigger the problem.
  • Strange noises coming from the AC: Finally, you may also hear strange noises coming from your air conditioner. Although these noises can mean various issues, a wheezing fan is often a sign of distress, alerting you that your unit is frozen and blocked.

What Happens When an Air Conditioner Freezes Up? The Dangers 

Several things can go wrong when the air conditioner freezes up. For one, a frozen AC system means you may not get enough cooling anymore or may get no cooling at all. This can cause serious discomfort if you’re in the heat of the summer.

Another common problem is fan damage. Running the AC fan even when the unit is frozen almost always results in a broken fan. Granted, replacing the fan isn’t very expensive. However, it’s an unnecessary cost.

Worse still, a broken fan can cause many other damages inside the AC. For instance, a broken fan can easily result in overheating. This is because the fan’s motor needs cool air to keep the temperature at the moving part down. Without that, the parts can overheat.

A frozen air conditioner can also cause condenser coils to expand and burst in extreme conditions. Surprised? It happens more than you think. If the coils freeze thus expand at different points simultaneously, the pressure between the expansion points can cause the tubes to swell and burst. If your air conditioner condenser tubes burst, that unit is gone. You must replace the whole outdoor unit.

What to Do When Your AC Freezes Up

You need to do several things if you suspect or have confirmed that you have air conditioner freezing.

  • Stop further freezing. The easiest way to do this is to shut down the air conditioner. It’s dangerous to keep running a frozen AC.
  • Unfreeze it. Check below for the step-by-step process to unfreeze a frozen air conditioner. It’s pretty straightforward.
  • Try to pinpoint the underlying issue. Why is your air conditioner freezing? Locating the underlying problem can help prevent future AC freezing.While you wait for the ice to melt, find the condensate drain and make sure it isn’t blocked. Consider opening up the ductwork so you can suction out the water.
  • Ensure proper maintenance. One of the easiest ways to prevent issues such as AC freezing is to ensure regular maintenance.

How to Unfreeze an Air Conditioner Fast

If you believe that you have a frozen air conditioning unit, you can take certain steps to get on top of the situation and possibly even get the heater back up and running. Here’s what to do step-by-step.

Step 1: Shut it Off

When your air conditioner freezes, the first thing to do is turn it off. The reason is simple – running a frozen AC strains the compressor. A strained compressor can overheat and possibly even break down. Replacing a broken compressor is very expensive. Moreover, running a frozen AC can worsen the freezing. So, begin by shutting off the air conditioner’s power supply at the electrical breaker.

Step 2: Let it Thaw 

With the power switched off, allow the air conditioning system to shed off the ice. Fortunately, you don’t necessarily need extra effort to thaw an AC. It will thaw naturally as long as the sun is up. You just need to be patient. Typically, you may wait a few hours to a full day, depending on outdoor temperatures. Regardless, don’t be tempted to break down the ice with a heavy object or sharp tool.

Step 3: Dry the Surfaces Manually 

Once the ice has completely melted away, it’s time to dry the surfaces, especially the wet exterior surfaces and moist condenser coils. We recommend using paper towels. Alternatively, air out the unit in the sun to dry. You can also use a soft piece of dry cloth to wipe down excess moisture.

Step 4: Run the Fan 

One way to thaw the A/C quicker is to use a blow dryer on the evaporator coil. You can also turn on the air conditioner fan without running the compressor so the ice melts faster. Restore the power (switch it back) and set the AC to run on the “FAN” setting. This engages only the fan but not the cooling mechanism. Let the air circulate throughout the AC and your home for at least five minutes to fully dry any remaining parts inside the AC and remove the excess moisture in your home. With that done, your AC is ready to resume normal duty.

Can I Pour Water on a Frozen AC?

Yes, it’s generally considered safe to pour hot water on a frozen air conditioning unit. The heat can help accelerate the thawing process.

However, beware that pouring hot water on the AC is rarely the magic pill many homeowners think it is. While it can help raise temperatures inside the AC, thus hastening the thawing process, it cannot instantly cure the problem. As such, it may not even be necessary in the first place.

That’s because a “frozen AC” essentially means that the condenser coils are frozen. So, to unfreeze the unit, you need to attend to the coils. Unfortunately, AC condenser coils are tucked away inside the outdoor unit. The hot water will certainly not reach the coils. Instead, you’re hoping that the heating effect reaches the frozen coils via conduction and convection. This happens easily. But how much heat can reach the coils? Impossible to tell, right?

Worse still, hot water is a danger to your health and life. Scalding is a real possibility. Or you may burn someone else.

For this reason, we only recommend pouring hot water if you can see ice over the outdoor unit. In this case, even lukewarm or room-temperature water can help melt away some of the ice to kickstart the thawing process.

Otherwise, consider safer and more practical thawing solutions such as turning off the AC and letting it rest as it thaws naturally or running the fan.

How Long does it Take for an AC to Unfreeze?

Generally, it takes between an hour and 24 hours to unfreeze a frozen air conditioner. It comes down to several factors, including the intensity of the problem and prevailing weather conditions.

For instance, if the freezing is so bad that you can see ice on top of the outdoor unit, you need to be prepared to wait a little more than an hour. On the other hand, it takes a much shorter time if it happens on a very hot and windy day.

Finally, the time it takes to thaw a frozen air conditioner completely depends on the thawing methods used. For instance, pouring hot water over the unit can cut the thawing time by a few hours. Similarly, blowing a fan next to the compressor unit can reduce thaw time.

How Do I Keep My Air Conditioner from Freezing Up?

First off, yes, you can prevent the AC from freezing. Although sometimes it happens out of nowhere, fixing the common causes early can significantly reduce the chances of a freeze-up. Here’s what to do;

1. Change your Air Filters Regularly

One of the main causes of air conditioner freezing is a dirty air filter. The air filter traps dust and other impurities in the supply air, i.e., the air entering your AC. However, warm air cannot enter the AC if you have a dirty air filter.

This can cause trouble as the very cold refrigerant in your condenser coils need the heat to turn to high-temperature liquid. Without the heat, you’re staring at the risk of extremely cold conditions inside the condenser lines, potentially causing freezing.

Keeping your AC air filters clean and replacing them as frequently as the manufacturer recommends can save you the trouble.

2. Clean the Fan Regularly 

The fan is just as important. It does three things. First, it creates the motion that helps draw warm air into the air conditioner for cooling. Secondly, it forces the warm air over the condenser coils where the heat is extracted.

Finally, it sustains the airflow that directs cool air out of the AC and disperses it throughout the intended spaces. Therefore, airflow into the AC and over the cold condenser coils is compromised if the fan is defective. This can cause the air conditioner to freeze.

For this reason, it’s very important to make sure that the fan is working optimally at all times. Make sure it’s clean and oil, or replace it when it begins to falter.

3. Keep your Vents Open

Many users are tempted to close one or two supply vents to lower energy bills. While this isn’t a completely wrong line of reasoning, closing air supply vents can lead to poor airflow, with many untold consequences.

For instance, weak airflow, as we’ve seen, can deny the cold refrigerant the heat it needs to evaporate. Keeping the cold refrigerant in an even cooler environment can easily lead to freezing.

So, the best solution is to keep all your supply vents open. However, if you’re worried about the energy bill, close only some but not all the vents. Always leave at least two vents open to prevent low airflow.

4. Keep the Condenser Coils Clean 

You’re probably wondering how dirty condenser coils can cause freezing. It all has to do with heat transfer between the condenser coils surfaces and the warm air circulating over the coils. Although the coils, typically copper or aluminum, have very high heat transfer, a film of dust over the coil can significantly compromise the transfer. In fact, you may even start getting not-so-cool air from the return vents.

The only way to prevent this issue is to regularly clean air conditioner coils for maximum heat transfer. Additionally, notice increased heating efficiency.

5. Schedule a Professional Inspection 

If you still don’t call the HVAC technician for an inspection at least once every year, you’re doing a massive disservice to your air conditioner. First, scheduled inspections are an opportunity for the technician to tune up your AC for maximum performance for the rest of the year. Efficient cooling throughout the summer can significantly lower your energy bills and operating costs in general.

More importantly, scheduled inspections often uncover hidden air conditioner malfunctions, such as low refrigerant levels, that may become big problems down the life. A low refrigerant level usually results from a refrigerant leak. Fixing this issue early can save you from a frozen AC down the line.

Calling an HVAC Professional: When to Seek Expert Help

The good news is that you rarely need professional assistance to fix AC unit freezing, as long as you follow the steps discussed earlier. However, if it’s been more than 24 hours and the ac freezing is still visible, then you should seek professional help. Similarly, consider calling an HVAC professional if there’s already internal damage, such as a broken fan. Maintenance Scheduling a routine preventive maintenance inspection is the best thing homeowners can do to keep their HVAC system operating at peak performance and extend its lifespan