Air Conditioner Freezing [Problems & Solutions]

If you find your air conditioner freezing, finding the source of the problem is crucial. Learn more about what to do in this article.

air conditioner freezing

Air Conditioner Freezing Up – Outside Unit 

The outside unit of your air conditioner may be freezing for several reasons. One important reason is that the refrigerant temperature is dropping or there is a loss of gas. But before you settle on this issue, which is the most severe one, check the air filter, air vents, and evaporator coil. These parts are likely to cause the outside unit to freeze if you do not service them. Turn off the air conditioner and leave it to thaw if you find the outdoor unit frozen.

1. Air Filter

The filter processes the air that goes into the unit so that it comes out cool after the refrigerant absorbs the heat in it. Typically, the warm air flows over the evaporator coil while the refrigerant is in it, and as it does so, the refrigerant cools it. However, if there is no warm air flowing over the coil, the refrigerant in it remains cold and causes the temperature to drop due to a lack of warmth. 

This, in turn, causes the air conditioner to freeze, even outside the house, if the trend continues. One reason this may happen is a dirty air filter; it restricts the free flow of air and causes the refrigerant’s temperature to drop. Therefore, disconnect the air conditioner from electric power and open the indoor unit or air handler. The air filter is inside the indoor unit and should be one of the first components you see once you remove the front panel or grille.

Remove the filter and clean or replace it, depending on the type and usage. There are reusable and disposable air filters, although it is recommended that you replace them after three to six months, no matter the type. If the filter has not been in use for long and is the reusable type, clean it with soap and water. But if it is the disposable type, discard it and replace it with a suitable part.

2. Air Vents

Obstructed air vents can cause the air conditioner to freeze. The unit pulls in warm air through the vents and passes it over the evaporator coil for cooling. If there is not enough warm air in the air conditioner, the refrigerant continues to get colder and eventually freezes the system. This issue is much like when there is a clogged air filter, but if the filter is clean, ensure the vents are open, and nothing is obstructing them. 

You may have to rearrange curtains and furniture to accommodate the air conditioner if necessary. Check both the supply and return vents if you have a central air conditioning system because the same issue can come up if one or the other is shut.

3. Evaporator Coil

The air quality in your home can drop if you have a lot of people moving around or going and coming. It encourages pollutants and contaminants, and over time, dirt settles on the evaporator coil. The chances of the coil getting dirty increase if the filter is also dirty. Dirt acts as a blanket that prevents the refrigerant from cooling the warm air. 

As a result, the coil freezes due to the low refrigerant temperature. So, inspect the evaporator coil to see if it is dirty and clean it if necessary. You can use a non-rinse foam cleaner designed specifically for evaporator coils or get professional assistance for the job. It is always best to hire an HVAC technician to clean coils because of their fragility and importance.

4. Thermostat

The thermostat that controls the air conditioner may malfunction and run all the time, even when it should cycle the air conditioner off. As a result of the constant operation, the temperature drops, and the system freezes. This is not a usual occurrence, so you may not think to check the thermostat. However, if the evaporator coil and filter are in good condition, there may be a wiring issue with the thermostat. Consider recalibrating the thermostat or replacing the component if calibration does not work.

5. Temperatures

The temperature outside the house may be too low to run an air conditioner. Typically, an air conditioning system functions best when the temperature is under 60 degrees Fahrenheit. Your location, time of year, and the time of the day also play a role in whether or not the outdoor unit freezes.

Temperatures tend to drop during the night, and if it is autumn or winter, the unit is likely to freeze. Living in colder regions makes this even more possible as the cold air prevents adequate warming for the coils and pipes, leading to freezing. Turn the air conditioner off if you notice it freezing, and leave it off until it thaws.

6. Refrigerant

A loss of refrigerant from the sealed system causes the pressure to drop until the outside, and indoor units begin to freeze. It means there is not enough gas to absorb the heat from the air, which leaves the refrigerant cold. Over time, the temperature continues to drop as less is absorbed until the system freezes.

The sealed system should have no leaks, and you should not have any need to recharge the system for as long as you own the air conditioner. However, there may be punctures in the refrigerant lines or coils, whether inside or outside. If you suspect a sealed system leak, turn off the air conditioner and get immediate assistance from a qualified HVAC technician.

Air Conditioner Freezing Up in Winter – Outside Unit

Dirty air filters, loss of refrigerant in the sealed system, poor maintenance, and closed air vents are some of the causes of the outside unit freezing in winter. Typically, the icy temperature should cause the unit to become significantly cold, but if you properly maintain the unit, it should not get to the point of freezing. However, if the cold weather comes with icy winds, the condensate from the air conditioner can lead to freezing.

Inspect the air filter to ensure it allows proper airflow during air conditioner operation. You should replace the filter every three months, whether or not it is reusable. While a clogged filter can restrict airflow over the evaporator coil, it can also cause the compressor to work harder, consequently creating more cold air than is necessary and freezing the unit. Therefore, replace the filter if it is clogged or damaged.

Next, check the air vents. Ensure they are open, clean, and unobstructed. If the vents are closed or have items blocking them, there will not be enough warm air for the air conditioner. Again, this causes the coils to freeze as the compressor works harder to produce cool air. The longer the air conditioner runs, the colder the refrigerant becomes. Clean the vents, open them, and move items away from the area if they are in the way.

Ensure the outdoor coils are clean for proper dissipation of heat from the air conditioner. If a significant amount of dirt blankets the condenser coils, they cannot efficiently remove heat, causing a rise in the temperature. As this restricts airflow, the compressor runs more than usual to maintain a cool temperature, leading to freezing. You can employ the services of a qualified HVAC technician to clean the coils or follow this guide for detailed instructions.

If the unit freezes, it should only be once in a while. However, there may be a defrost system that occasionally thaws the coils to prevent ice accumulation. The defrost cycle may run every half hour, hour, or ninety minutes, depending on the model. Nevertheless, it may not be sufficient to keep the outdoor unit from freezing if the temperature is icy.

Do not use hot water to thaw the unit; many homeowners resort to pouring hot water over the condensing unit for a quick defrost. But it only serves to damage vital components, although it may thaw the unit. Therefore, it is only a temporary fix as you may end up with a more severe problem.

Note: Schedule a visit for service on the air conditioner if none of the above works and you suspect a refrigerant leak. Turn off the air conditioner and open windows to allow proper air circulation while you wait for your technician.

Air Conditioner Freezing Up – Inside Unit

Poor or no airflow is the primary cause of an air conditioner’s indoor unit freezing. Check the air filter, drain pan, drain line, evaporator coil, ducts, vents, and blower. One more possible cause is a loss of refrigerant from the system. Turn off the cooling function and power the fan so that it melts the ice in the air handler. 

Allow it to run on On mode instead of Auto so that it can effectively melt the ice and dry the resultant water. This may take some time, but you cannot run the unit until it is completely dry. Then, start your troubleshooting steps from the simple ones.

1. Clogged Air Filter

The air filter is usually easy to remove. Open the front panel of the indoor unit and slide the unit out, although this step may vary by model. Inspect the filter and if it is dirty, replace it. But if you opt to clean it instead of replacing it, ensure you do a thorough job and allow it to air-dry before putting it back into the air conditioner. 

Dirt prevents air from flowing into the unit, which consequently causes the evaporator coil and other components to freeze due to too much available cold air. Therefore, regularly inspecting and cleaning or replacing the air filter in your air conditioner is crucial, and ensure you replace it with one that fits your air conditioner model.

2. Dirty Drain Pan

When an air conditioner operates, it produces some water that flows out of the unit into a drain pan. From there, the water flows out through a drain pipe and exits the air conditioner. If the drain pan is clogged with dirt, the water does not flow out and backs up into the unit, which may eventually freeze if the unit regularly runs.

Inspect the drain pan, which is usually under the evaporator coil. Consult the unit’s user manual for the pan’s location. Clean the pan if it is noticeably dirty and sanitize it; use mild soap and water or mix water and bleach to clean it. Allow the pan to air-dry before putting it back into the air handler.

3. Obstructed Drain Pipe

The condensate drain pipe is directly connected to the drain pan and is the primary reason for standing water in the pan. If the line is obstructed with dirt, the water in the pan does not have a suitable outlet. So, it backs up into the unit and freezes over time. Dirt and debris can build in the pipe and block it if the filter is dirty. The dirt can also affect the evaporator coil and increase the risk of freezing in the indoor unit.

After cleaning the drain pan, inspect the drain pipe, and if dirty, use a wet/dry vacuum to clean it. You can rent this type of vacuum if you have none, but there is also the option of using water and bleach to clear the pipe. It may take longer, but the bleach will sanitize the tube. Ensure water flows freely out of the tube by pouring some into the drain pan. Then, you can finish the task by cleaning any excess water around the pipe.

4. Faulty Blower

A faulty blower cannot circulate cold air from or draw in warm air into the air conditioner. Typically, the warmth in the air prevents the air conditioner from freezing as the refrigerant absorbs it. The blower, on its part, must constantly blow through the cooling and defrost cycles to ensure the air spreads. However, if it stops working, the cold air remains trapped in the air conditioner and eventually leads to freezing.

The blower may need some penetrating oil to keep the motor and wheel running. Apply gear oil to the motor and shaft for proper lubrication; it may be all the solution you need. If that does not work, touch the motor; a hot blower motor may indicate it has internal faults or damaged components. Consider replacing the motor if it applies. Otherwise, the problem may stem from a damaged control board, and you will need an HVAC technician to check and fix the issue.

5. Dirty Evaporator Coil

The evaporator coil may be dirty, and dirt on the coil causes it to freeze. The reason is that dirt restricts the refrigerant in the coil from releasing cold air, which traps it and leads to freezing. It is not typical for the evaporator to become dirty, but constant usage and poor maintenance can affect it. 

So, hire an HVAC technician to clean the coil or use a non-rinse foam evaporator coil cleaner for the job. Carefully clean the coil because it is fragile, and damage means replacing it or the entire unit, both f which are cost-intensive. Also, clean the area around the coil, including the blower, and replace the filter if necessary.

6. Blocked Vents

Open and clean all the vents in your air conditioner. Do the same in every room where the air conditioner supplies cold air, especially if the room is not frequently used. As with trapped air for a dirty evaporator coil, closing the vents, whether return or supply, affects the unit. It traps the cold air and causes the indoor unit to freeze because there is no outlet for the cold air. The same applies if the vents are significantly dirty.

7. Damaged or Obstructed Ducts

If your air conditioner uses ductwork, it may have dirt in it or is damaged. You may not know how to clean the ducts properly. Therefore, it is best to hire a professional to inspect the ducts and clean them if dirty or replace them if they are damaged. 

Warm air easily and quickly escapes from the ducts if they are leaking, which means the air conditioner does not have enough air to cool. And if there is dirt, it slows the flow of air and keeps the unit from working. Consequently, the indoor unit freezes.

The final part of the air conditioner to check is the sealed system. Refrigerant loss can affect the evaporator coil as it is not sufficient to absorb heat from the air, and as a result, the indoor unit freezes. It is recommended that you use the services of a qualified technician to fix refrigerant issues, according to the regulations on refrigerant and Freon usage. The technician should also check other possible causes of the freezing problem. Remember to defrost and dry the air conditioner before starting it again.

Air Conditioner Freezing Up at Night – What to Do

Several faults can cause an air conditioner to freeze at night. The primary cause may be the outdoor temperature, which tends to drop at night. When the outside air temperature is too low, the air conditioner should not run. Otherwise, it causes the system’s internal pressure to drop and encourages freezing. You may have to turn off the air conditioner or run it on a timer to turn it off automatically when you go to sleep at night.

1. Poor Airflow

Insufficient airflow can affect how well an air conditioner functions and can lead to freezing, even at night. Check the air filter and clean or replace it if dirty. Ensure you use the right type and size of air filter for your system; it may fail to function or have problems if you use the wrong type. 

But if you recently replaced it, it may be the wrong type or too small for the air conditioner. Before throwing out the old filter, check its dimensions and type, and consider using it as a reference to purchase a new one. Otherwise, contact the manufacturer or a trusted HVAC dealer for the correct replacement part.

2. Stuck or Broken Contactor

There is a small switch in the outdoor condensing unit called a contactor. It may stick or become broken, which causes the condenser to run all the time and freeze. Turn off the thermostat that controls the air conditioner and see if the condensing unit continues to run. If it does, you likely have a stuck or broken contactor. Disconnect the unit entirely from electric power by turning off the circuit breaker and get professional help for a replacement.

3. Defective Blower

The indoor unit may stop working while the condenser continues to run if the blower is faulty. And if the condenser runs without stopping, it will eventually freeze, or the system may fail. Turn off the air conditioner. Wait about five minutes, and turn it on again. Wait to see if the unit runs inside and outside, and if the issue continues, you may have a faulty blower motor. Replace the blower or hire a technician for the job.

4. Insufficient Refrigerant

The closed system may leak in one or more places. If you have had to recharge the system more than once in two years, there is a leak you must fix. Turn off the air conditioner and call for professional help. Otherwise, the pressure drops, and the refrigerant cannot absorb heat from the air, leaving too much cold air in the system. It is not healthy to have a gas leak in your home, and it is also destructive to your air conditioner.

Air Conditioner Freezing Up in Car – Fixed

Some possible causes for your car’s air conditioner are moisture, insufficient refrigerant, dirty air filter, clogged or faulty orifice tube or thermal expansion valve, and a defective blower motor.

1. Moisture

An air conditioner’s system works as a closed system that keeps the refrigerant in and contaminants out. That is why there is usually no need to recharge the system with refrigerant; it does not expire or reduce. However, a leak compromises the system and introduces pollutants into the closed system. 

Also, it lets moisture in, which increases the risk of freezing. Use professional auto mechanic help or try evacuating the closed system for about thirty minutes to dry the water. You will have to recover the refrigerant from the system before removing the moisture. It is best to allow a professional to repair the damage.

2. Dusty Air Filter

Your car’s air conditioning system functions well with proper airflow. The same applies to all types of air conditioners. If the filter is dusty or filled with debris, it restricts the flow of air and causes the evaporator coil to freeze. Over time, the cold temperature leads to an ice buildup. Remove the cabin filter and inspect it; if it is too clogged for you to see through it, replace the filter.

While checking the filter, it may be best to check the condenser and return vents. Dirt may be clogging them, and if that is the case, air cannot freely pass through, and heat cannot be efficiently dissipated. Clean the vents and ensure they are fully open. Also, remove every trace of dust and debris from the condenser for proper air circulation and heat dissipation.

3. Defective Thermal Expansion Valve or Clogged Orifice Tube

Every car does not have these two parts at the same time. Instead, it has one or the other, and the one it has depends on the make of the car and its model and year of manufacture. They are metering devices that control how the refrigerant flows in the closed system of the car’s air conditioner. 

Therefore, the system may not get enough refrigerant needed to run the cooling cycle if the orifice is obstructed or the expansion valve is defective.  And if the system does not have enough refrigerant, it freezes the coil and other components. Your auto mechanic should also check these parts along with the others to ensure they are in good working condition. They can replace the faulty parts or clean the dirty ones.

4. Faulty Blower Motor

If you recently replaced the air filter and the evaporator is not frozen yet, there is no airflow from the indoor vents, check the blower. It may have stopped working, or debris may be clogging it. The motor of the fan can become faulty due to overuse or overheating. If that is the case, the system can freeze because there is no airflow to disperse the cold air, resulting in freezing. You may have to replace the blower motor or the entire blower assembly.

5. Insufficient Refrigerant

Lastly, the closed system may have a low refrigerant charge. And if it is low, there will not be enough refrigerant to absorb heat, which builds condensation on the evaporator coil and leads to freezing. Moreover, the temperature of the refrigerant drops due to insufficiency, which causes the system to freeze. Let your auto technician check the refrigerant level and make the necessary repairs if there is a leak in the system.

Air Conditioner Freezing Up in Camper – Solved

The primary reason the air conditioner in the camper freezes is poor airflow. The same is true for all types of air conditioners. Poor airflow leads to other issues in the unit, which contribute to freezing problems in the system. Some of the most likely causes of restricted airflow are clogged filters and dirty evaporator or condenser coils. Another possible cause is a loss of refrigerant, but it does not always happen.

So, locate the filters in your air conditioner and remove them. If they are filthy, replace them unless they are still usable. Ensure they are clean if you are still using the old filter, and open the supply vents. But replace the filters every month or 6 weeks. Turn on the fan and use On instead of Auto to keep it running until the ice melts from the air conditioner.

Also, check the condensate drain and pan. First, ensure the air conditioner is at the correct angle, especially if it is a window or wall unit. There must be proper drainage to keep the air conditioner from freezing or switching off. Clean the drain pan and clear the drain tube; it may be clogged with debris, causing the water to flow back into th air conditioner and eventually freeze. Regularly check the drain pan and tube to keep it clean and the water flowing; do this once a week.

Another possibility is that the system is leaking. If you are unsure, turn off the air conditioner for some time until a technician can properly check the system. Insufficient refrigerant can keep the system functioning poorly and may eventually lead to freezing if it is not recharged.

Air Conditioner Compressor Freezing Up – Quick Fix

Some of the reasons your air conditioner compressor freezes up are clogged filters, a faulty thermal expansion valve, too little refrigerant in the system, a dirty evaporator coil, and a defective blower motor. Contact the manufacturer for professional assistance if you notice the compressor is freezing up, or follow the steps in this article to fix each possible problem.

Symptoms of Frozen Coils in an Air Conditioner

You will notice that the air conditioner has a noticeably reduced airflow where it used to produce adequate air. You may also notice the outdoor unit constantly running instead of cycling on and off as the air conditioner cools the room. 

After some time, the airflow may reduce even more, and there may be signs of freezing. If left without repairs, the system may become frozen, and the unit will stop producing any air. Frozen coils mean the air conditioner has no proper airflow, which drops the refrigerant’s temperature past the freezing point. 

You risk total system failure if there is no repair on the frozen coils; the drop in temperature may come from a refrigerant leak. Such a leak is dangerous to you and everyone else in the house, especially if it comes from the indoor unit. The leak may also damage the air conditioner in the long run.

How Do I Keep My Air Conditioner from Freezing Up?

Regular maintenance helps you keep your air conditioner from freezing up. If it is winter, the outdoor unit is likely to freeze, even with an automatic defrost system. It is best to turn on the unit only intermittently or cover the outdoor unit if it is not in use. If you are using it as a heating pump, the cold air blows out from the condenser while the warm air blows from the indoor unit. As a result, the outdoor unit is more likely to freeze when used as a heater.

Also, check the air vents to ensure they are fully open and unobstructed. This ensures the cold air finds a way to leave the air conditioner so that it is not trapped and leads to ice accumulation on the coils. The ductwork should not be damaged; otherwise, the air finds an outlet, reducing the available air for the air conditioner. Repair the ductwork or clean it with the help of an HVAC technician.

Replace the air filter every three months, but the frequency of replacement depends on how often you use the unit. Frequent usage may cause the filter to clog quickly, more so if there are many people and pets around the house. Some types of air conditioner filters are more sophisticated than others, so they last longer. If you use such air filters, you may not need to replace them for six months or more.

Inspect the condensate drain line and pan to ensure they are not clogged. A clogged drain will not let water out, increasing the risk of freezing. Clear out the line with a wet/dry vacuum or use a mixture of water and bleach to remove debris. Also, clean the drain pan and sanitize it; do this every one or two weeks.

Furthermore, inspect the blower and evaporator coil. If the blower has issues, such as debris or a blown motor, there will be no air circulation, and the coil is likely to freeze. And if the evaporator coil is dirty, which may happen if the filter is significantly dirty, it restricts the cool air from the refrigerant and accumulates ice. Clean the blower and replace the motor if it is not running. Use an evaporator coil cleaner to remove dirt from the coil if it appears to be freezing and all else fails.

However, check for leaks in the refrigerant lines if nothing else seems to fix the problem. Refrigerant leaks also cause the system to freeze, although it is not a regular occurrence. An air conditioner’s closed system rarely springs a leak unless you accidentally puncture the lines or coils while cleaning. So, it may not be the first thing you check until you exhaust other options. Then, you can hire an HVAC technician to check the refrigerant pipes and repair possible leaks.

Air Conditioner Frozen in Summer – How to Fix

An air conditioner freezes in the summer due to low refrigerant or a lack of proper air circulation. It may come as a surprise that your air conditioner can freeze in the hottest of weather, but you tend to use the system more when the weather is hot. So, the refrigerant runs more and produces more cool air than usual. And if this cool air does not have a proper outlet, it reduces the temperature of the refrigerant and causes the system to freeze.

Poor airflow is typical in hot weather because the air filter clogs quickly with dust and debris. The evaporator coil is also likely to clog with dirt, especially from the excess on the air filter. It is crucial to check the filter and replace it every month while it is summer. It helps to keep the airflow properly circulating and the coil free of dirt. Clean the coil and replace the filter; use professional services for a more thorough job.

You can check the blower to ensure it is running, especially when the air conditioner is operating. The blower has the job of circulating the air, blowing cold air out, and transporting warm air over the evaporator coil for cooling. If the blower wheel is clogged or the motor stops running, there will be an air restriction, which affects the cooling function. 

A restriction in the airflow increases the risk of freezing in the air conditioning system. Place your hand over the supply vents to see if there is airflow. If there is none, the blower is not working, and the evaporator coil may be frozen. But if there is airflow, the blower is working but check whether or not the air is cold. Clean the blower if dirty or replace the blower motor if it does not work.


However, if none of the above applies, check the refrigerant. This may not be a task to do yourself because you need special equipment for checking the refrigerant level. That is unless you have the skillset and training to handle such a leak. 

You can try using a detection kit or soapy water to test for a leak, but it is important to use professional services for proper leak detection and repair. In some cases, it may require a replacement of the entire air conditioning system. Turn off the air conditioner while you wait for assistance; the longer you run it, the more it will leak refrigerant.

RV Air Conditioner Freeze Sensor Location

The freeze sensor on an RV air conditioner is typically located on the evaporator coil. Open the front panel of the indoor unit and find the evaporator coil. You may have to remove the filter to access the coil, and it may be the best time to clean or replace the filter if necessary. 

The sensor is clipped to the coil; it is usually about the size of a quarter and has two wires attached to it. The user manual may also have instructions directing you on where to find the sensor for your specific RV air conditioner.

RV Air Conditioner Spitting Ice – Solved

Once you notice your RV air conditioner spitting ice, turn off the unit. Disconnect it from electric power; you can turn off the breaker controlling it. Leave the unit off for a few hours until the ice thaws; you can use the fan mode to speed the thawing process. Remove the air filter and discard it or clean it if it is still usable. 

If you must reuse it, ensure you thoroughly clean it and allow it to air-dry. However, these are only temporary fixes. It is crucial to get to the root of the problem, and it means finding out why there is ice in the air conditioning system. When ice forms inside the air conditioner, it points to poor airflow. The usual culprit is the air filter, which may be clogged with a significant amount of dirt. 

Also, the blower may be faulty, or the evaporator coil may be dirty. Fixing these possible causes helps reduce ice formation inside the air conditioner. But the system can leak refrigerant, which typically causes the pressure to drop and build ice on the coil. Only a professional HVAC technician can correctly check and fix a refrigerant leak problem.

Can You Store an Air Conditioner in Freezing Temperatures?

You cannot store an air conditioner in freezing temperatures. If the weather is cold and you need to store your air conditioner, it is crucial to find a warm place. Otherwise, the coils freeze to the point of irreparable damage. Also, there are ways to winterize an air conditioner if you want to protect it from icy temperatures.

It is easier to remove some air conditioner types for proper storage, but air conditioner removal is not always convenient. Therefore, you may have to use a winterizing cover to protect the outdoor unit from icy weather and winds, as well as debris and insects while it is not in use. However, if you can remove the unit, ensure you thoroughly clean it before storage. Put it in a box, seal it, and store it in a cool, dry area of the house, where there is not much traffic and away from other objects.

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