Why Is My Central Air Conditioning Line Freezing Up?

Nick Durante
by Nick Durante

Central air conditioning is a modern commodity and it’s hard to get comfortable when it isn’t working properly. HVAC system problems can be overwhelming and even expensive, especially if you don’t know what you’re doing. So, why is your central air conditioning line freezing up?

Low and leaking refrigerant are the most common reasons why a central air conditioning line is freezing up. Your lines can also freeze if the ducts are clogged with debris, dust, and dirt and you need to clean them. Replace your air conditioner’s filter every 3-6 months because your lines will freeze up if they are clogged.

Your HVAC system won’t work properly if the lines are frozen, and it can make your home uncomfortable. Luckily, you can diagnose the problem without professional help if you know what to look for. Follow along as we explore why your central air conditioning line is freezing up.

Why is my Air Conditioner Line Covered in Ice?

An air conditioner line covered in ice indicates that your evaporator coils are too cold to operate properly. A frozen central air conditioning line can prevent your HVAC system from working properly. You will typically notice that your AC lines are frozen when heat comes out of the AC when you are expecting cool air.

There are several reasons for your central air conditioning line freezing up. You don’t need to hire an HVAC professional to identify the cause of the problem. Luckily, it doesn’t take much time to figure out what’s wrong if you know what to look for.

Clogged Ducts

Unfortunately, an air conditioner’s ducts are susceptible to clogging because of dirt, dust, and debris. Air won’t be able to pass through the ducts as well as it should and it will affect your HVAC system’s performance. This will prevent warm air from passing through the system and your evaporator coils can freeze.

You should clean your AC ducts every 4 years on average or sooner if you notice that they are obstructed. It is ideal to hire a professional to clean your AC ducts because it can be difficult. Homeowners can expect to spend $300 or more to hire a professional to clean their air conditioner ducts.

Damaged Blower

Every HVAC system relies on a blower to circulate air throughout your home. The motor is the most important aspect of the blower, ad the system won’t work properly if it’s damaged. A blower’s motor is the component that brings in and circulates the air.

Evaporator coils need air to come in and out constantly so that they don’t freeze. The lack of airflow will cause your evaporator coils to freeze eventually. Luckily, you can replace your blower motor for $450 or less and you won’t have to worry about the coils freezing again.

Dirty Filter

A clogged air conditioner filter will restrict airflow throughout the system. Excessive dirt and dust on a central AC filter will prevent warm air from circulating. This will eventually cause your evaporator coils to freeze, and it will happen quickly in the fall or winter.

Dirty AC filters will also reduce the air quality in your home, which is bad for homeowners with respiratory problems. This is one of the easiest fixes and all that you need to do is replace your AC filter for under $10. Make sure to replace your AC filter every 3-6 months so it doesn’t become clogged and your evaporator coils won’t freeze.


Refrigerant is a key component of any HVAC system as long as the levels are where they should be. Low levels of refrigerant can cause your evaporator coils to freeze. The same thing can happen if your refrigerant is leaking within the system.

An HVAC system needs refrigerant to both heat and cool your home. You can hire a professional to fix the leak or add more refrigerant so that the system can heat and cool your house as it should. This will prevent your evaporator coils from freezing.

How do You Fix a Frozen AC Line?

You can temporarily fix a frozen AC line if you thaw it out. This fix won’t solve the problem, but it will buy you time while you figure out the cause. Turn on the fan without running the air conditioner for a few hours so the line can thaw out.

During this time, you should check for refrigerant leaks or check to see if you need to add more. Otherwise, you can use this time to call a professional to get help. You will be able to run your thermostat like usual once you get to the root of the problem, but thawing the line is a great temporary fix.

How do I Keep my Air Conditioner From Freezing up?

The best way to keep your air conditioner from freezing up is to inspect it regularly. This is especially necessary if you live in an older home or your HVAC system has been there for a long time. Check your vents every few months to make sure that they aren’t clogged with debris, and clean them with compressed air if they are.

Keep an eye on the refrigerant levels as well to make sure that they don’t get too low. There is most likely a leak if you have to replace the refrigerant too often. Regularly replace your AC filters at least twice per year to prevent freezing and keep your HVAC system working properly.

Summing it Up

Leaking refrigerant can cause your central air conditioning line to freeze. Your lines can also freeze if you are running low on refrigerant and you need to add more. Otherwise, you may need to clean out your AC ducts if they are clogged.

Replace your AC filter if it is dirty or you haven’t replaced it in 3-6 months. Shut off your air conditioner and run the fan to thaw out the lines while you figure out what caused the lines to freeze.

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Nick Durante
Nick Durante

Nick Durante is a professional writer with a primary focus on home improvement. When he is not writing about home improvement or taking on projects around the house, he likes to read and create art. He is always looking towards the newest trends in home improvement.

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