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Frozen AC Line: Why It Happens & What To Do About It

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

An AC line is frozen when there is ice inside the pipes. When the temperature drops below 32 degrees Fahrenheit, water inside the pipes begins to freeze.

This causes the pipe to expand and become brittle. Once the pipe cracks or breaks, you’ve got trouble.

How Does An Air Conditioning Unit Work?

Air conditioners remove heat from inside buildings by transferring it to the outdoors.

There are four main components of an air conditioning system. These are the evaporator coil, compressor, condenser, and refrigerant.

Warm indoor air is drawn in through a fan, and blows over the condenser coil.

The heat is released into the atmosphere as warm air. The air is cooled by the compressor and circulated around the house.

When the refrigerant reaches the condenser, the heat is expelled out of the system.

This causes the refrigerant to change back into a gaseous state. Then, the refrigerant returns and repeats the process.

When Your AC Line Is Frozen This Is What Is Likely Happening

When Your AC Line Is Frozen This Is What Is Likely Happening

Your AC is frozen because there is something wrong with it. You need to take it apart and clean it.

Then you need to replace some parts or repair them. Here are some of the things that can go wrong.

Poor Airflow Over Coil

When the evaporator coils become too cold, the ac units pipe freezes. Refrigerant fills the evaporators inside the air conditioning unit.

The ac unit pipes freeze because the evaporator coils are too cold.

The AC system (see also ‘Guide On How To Vacuum AC System Without Pump’) works by extracting the warm air from inside the house and sending it through the air conditioner where the coils cool the warm air. Then the AC unit redistributes the cooled air back into the home.

Poor airflow causes the evaporator coil to get too cold, which could damage the condenser. Copper pipes (see also ‘How To Measure Copper Pipe in No Time‘) freeze when there is insufficient airflow.

Dirty Air Filters

Air filters should be replaced every month. Failure to replace them can lead to airflow problems that may cause your evaporator coils to freeze over.

Ice buildup on your air conditioner will be more obvious than if you opened the unit up to see the coils.

Dirty Air Filter

You should change your air filter every month. If you don’t, it could cause your car to overheat and stop working properly.

What To Do About It

Air filters should be cleaned regularly. If you’re using an air conditioning unit, you’ll want to clean the coils as well.

Leaving them set to high for two hours will help draw warm air into the system, helping to thaw the coils.

Make sure the supply vents are clear of dust or debris before switching the unit back to its regular settings.

You should replace your air filter regularly. If you’re having trouble getting rid of mold spores, try using an ozone generator or a humidifier (see also ‘ How Long To Keep A Humidifier On ‘). If you want to get rid of mold spores, use a humidifier (see also ‘ Humidifier Leaving White Dust ‘).

Low Refrigerant LevelsLeakage

Your air conditioner is running out of refrigerant. You need to order more.

What To Do About It

Air conditioning systems run on a closed loop. Refrigerant doesn’t leave the loop. If there is a leak, it needs to be fixed.

Recharging the system won’t fix the problem. Leaks can harm the environment and people in the house.

You should check if there is a leak in your air conditioning system before calling an expert.

Switch the thermostat to the OFF position first, then turn the fan speed up to high. Let the AC run for two or three hours, so it can cool down.

Improper Temperature Setting

Air conditioning units are designed to work properly when temperatures fall below 60 degrees Fahrenheit.

Running an AC unit when it’s cold out could lead to problems such as frozen parts.

What To Do About It

Air conditioning is very useful in summertime. You should turn it off when winter comes around.

Faulty Or Dirty Blower Fan

Faulty Or Dirty Blower Fan

Your air conditioner will be working fine if your blower fan’s blades aren’t clogged up with dust or debris.

But if they are, then your air conditioner won’t circulate enough air. That’s why your air conditioner freezes up.

A broken fan won’t be able to send enough heat over the evaporator coil, so your AC system will stop cooling your house. Your AC line could freeze if you don’t fix the problem soon.

What To Do About It

Air conditioning fans are often noisy. When they get old, they may stop working properly. Open up the unit as if you were going inside to do an internal cleaning.

Clean the fan blades. If the fan is still making noise, call a technician. If the fan is dusty, wipe it off. If the problem continues, contact a technician.

Supply Vents Are Closed

Closing supply vents in unused rooms may cause your air conditioning system to overheat and shut down. This could result in higher energy bills.

Return Vents Are Blocked

Vents are used to suck air into units and play an important role. They can also become blocked and lead to malfunctions.

Dirty Evaporator Coil

Air filters need to be changed regularly. Dirty coils will stop airflow. Make sure all vents are open and unobstructed.

Low Refrigerant Levels

Low refrigerant levels are typically due to leaks in the system. Higher energy bills, hissing noises, and cooling systems blowing warm air (see also ‘AC Blowing Warm Air In House: 8 Possible Reasons & Solutions‘) are symptoms of low refrigerant levels. A professional will be capable

Act Fast When You Have A Frozen AC Line

Act Fast When You Have A Frozen AC Line

A frozen air conditioner line shouldn’t be ignored. Running an air conditioner when it’s frozen can cause permanent damage.

Repairing the damaged part instead of replacing the entire unit is often too expensive.

Your air conditioning system needs maintenance when this happens. You should call an AC repairman as soon as possible.

Don’t ignore an AC line that’s frozen; deal with it right away. If you leave your refrigerator running while its components are locked up, it can cause the compressor to become stressed.

If you leave your system like that for too long, the more likely you are to damage it permanently.

Replacing a damaged compressor rather than the entire system is often too expensive for most people, meaning this can end up costing a lot of money.

First, check if there is any dirt or debris inside the vents. Clean them out thoroughly.

Next, make sure that the filter is clean and replace it if necessary. Finally, make sure that the thermostat is set correctly.

Thawing Your AC Line

DIYers should turn off the thermostat before thawing the AC unit. Turning the fan to the ON position will help warm up the system.

Thawing the system will cause a lot of water to be produced. This water must be drained or else it will cause serious water damage to your house.

You should always hire a professional to do your AC repair work. A professional will know what needs fixing and how to fix it correctly. Hiring a professional can save you money and time.

Good technicians will replace your filters if they haven’t been replaced yet, in addition to anything else required to fix the problem.

You should always choose an HVAC company that has been around for a long time. This ensures that they know what they’re doing. Also, make sure that they offer free estimates.


Air conditioners use refrigerants to cool your house. When you turn on an air conditioner, it releases this refrigerant into the atmosphere.

This refrigerant then goes around the house cooling everything down. If there is a problem with the system, the refrigerant will not circulate properly, causing the air conditioner to stop working.

You should be able to achieve cooling by turning off your air conditioning unit’s fan.

The fan mode setting should be set to the lowest speed possible. If you’re using the fan mode setting (which is the default), it should only take 2 or 3 hours.

Until you’ve addressed whatever caused it to stop working, you shouldn’t return the unit to its original setting.


A frozen AC line can be a nightmare. Hopefully, our guide has helped you learn how to diagnose one, and how to get it fixed!

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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