AC Unit Frozen? | Common Reasons And Troubleshooting Tips

AC Unit Frozen? | Common Reasons and Troubleshooting Tips

Anthony Barnes

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A frozen AC unit is a common problem in homes, but it’s not always easy to diagnose the issue or fix the problem without professional help.

AC Unit Frozen? | Common Reasons And Troubleshooting Tips

This article discusses some of the most common causes for an AC unit to freeze up and how to troubleshoot your own system.

It also includes tips on preventing this from happening again, plus information about getting repairs done right.

If you need immediate assistance, contact us today! 

What Is Causing My AC Unit To Freeze?

It’s important for an air conditioner to be working properly, especially in the summer.

No one wants to be sweating uncomfortably in their own home.

However, since AC units are machines, there will always be some possible technical issues you can run into.

System issues are pretty common, but that doesn’t make them any less annoying to deal with.

A unit that freezes up is one of the most common issues that people deal with.

So, if this has happened to you, don’t worry – you aren’t alone! There’s a lot that you need to know when it comes to AC units, and it can take time.

We’re going to be going through some troubleshooting tips you can try at home if your AC has frozen up (see also ‘Frozen AC Line: Why It Happens & What To Do About It‘).

Each of these issues are pretty common, and most of them can be fixed with a few simple adjustments. 

It’s easy to do AC repairs when you know what to look out for, so you may need to take your time to figure out what the issue is.

If you don’t have the time to do it yourself, get some professionals to check.

Some of the most common problems with AC units include poor airflow, dirty coils, and a frozen evaporator coil.

However, don’t worry if you don’t know what to look out for.

Bad Airflow

Since airflow is a crucial part of an air conditioning system, the unit will not work properly if there is no proper airflow.

In other words, if there isn’t enough cool air flowing inside the house, then the air conditioner won’t be able to keep your home comfortable.

To ensure that the air is moving freely around inside your home, check to see that all the vents are open and that they aren’t clogged up.

Also, make sure that the filters in the HVAC system are clean and that the air filter itself isn’t dirty.

Blocked Coils

The coils of an AC unit can easily be blocked by debris and dust. The best way to prevent this is to have regular maintenance performed by a pro.

When the unit needs cleaning, have your technician look at the coil first.

If there is something stuck in the coils, you’ll want to get it out before the coils become damaged.

Otherwise, you may need to replace them altogether.

Low On Refrigerant

Refrigerant is essential in AC units, as it keeps the cooling process running smoothly.

Refrigerants are chemicals that are used to absorb heat from the air. 

When refrigerant levels drop too low, the cooling process slows down or stops completely.

Fortunately, this condition is relatively easy to repair. You just need to refill the unit with new refrigerant.

When there isn’t enough refrigerant in the system, you will not get any cool air coming out of the vents.

Additionally, when there isn’t enough refrigerant, the temperatures inside the unit will fall into negative numbers.

When the evaporator coils get below freezing, the water vapor in the nearby area will attach to the coils and freeze over.

The frost can build up over time, leading to a thick sheet of ice forming over the coils.

The obvious solution to this issue would be to add more refrigerant. However, this should not be done.

This could be a sign of other issues, too, so it’s always best to call in professionals to get it checked out.

It isn’t uncommon for there to be a leak somewhere in the refrigerant lines, evaporator coil, or compressor.

Refrigerant leaks are difficult to deal with. Because of this, it’s better to call for professional services.

A Faulty Blower Motor

Air is blown over the coils within the system thanks to the fan and blower motor.

The fan pushes air across the coils, which helps to remove the heat from the room.

The blower motor turns the fan blades, allowing them to move the air around.

When the blower motor fails, the entire system shuts down.

You will probably notice a lot of rattling noise coming from the air conditioning units if this is the issue.

You should check the blower motor and the fan to see if this is an issue.

If everything works fine, then you can move onto the next possibility. 

A Dirty Air Filter

A Dirty Air Filter

Your air filter is another important component of your central air conditioner, because it allows fresh air to flow through the ducts and into your home.

If the filter gets clogged, it will block the flow of air, making it harder for the unit to function.

This is a very common reason for AC units freezing up.

Weak airflow can be a very unpleasant issue to deal with. Always make sure that your air filters are clean and in pristine condition.

If they aren’t, clogged filters will result in  some serious problems. You also want to keep an eye out for signs of mold growth.

Mold spores can grow in humid areas, and they can cause all sorts of health issues.

So it’s best to make sure that these areas are cleaned off regularly.

Check The Air Ducts

It’s possible that the air being pulled through the ducts is dirty. If this is the case, you’ll want to have it fixed right away.

Some homeowners even find that their air conditioning systems don’t work properly after a long period of time due to dirt buildup.

To keep things working well, it’s recommended that you clean the ducts every few months.

Not only can there be blockages in the air ducts, but leaks, too. Either of these will result in bad airflow.

If you notice that there is something wrong with your air ducts, schedule an appointment with a professional.

Air ducts can be very tricky to work with, so it’s always better to get a professional involved for the best results.

The Fan Isn’t Getting Enough Power

It’s common for the electrical system in a home to be at fault.

If the fan doesn’t seem to be getting enough power, it may be an issue with its wiring.

While it might sound like a simple fix, it’s actually quite complex.

In order to determine whether the problem lies with the fan itself or the wiring, you need to consult a professional electrician.

They’re able to pinpoint exactly what’s going on, and they’ll know how to repair it correctly.

If you think that this issue is causing your AC unit to stop running, you should contact a professional immediately.

It could mean that your AC needs a new motor, or that something else is wrong with the unit.

Be prepared to pay a visit to the service center as soon as possible.

Troubleshooting Tips For A Frozen AC Unit

There are a number of troubleshooting steps you can take to figure out what the issue is.

Here are some things you can try if your AC (see also ‘Here Is What To Do When Your AC Blows A Fuse‘) is freezing up.

We’ll go through each option below in detail so that you can take a look at your own unit.

Look For Refrigerant Leaks

If your indoor temperature starts to rise without any other symptoms, you can assume that there is a leak in the refrigerant line.

The most likely culprit here would be a compressor clutch. These parts are used to regulate how much gas goes into the compressor.

However, if they are worn down or damaged, it won’t allow the proper amount of gas to enter the compressor. That means less cooling power than normal.

This is not something that you should do yourself if you are not experienced.

If you were to try doing this yourself, you would likely end up wasting a lot of refrigerants, which is not cheap.

The cheaper option would be to simply get a pro to do all the dirty work for you. That way, you will be saving money, time, and resources. 

It’s important to remember that, since the AC unit is actually a closed system, adding more refrigerant is never recommended.

Even the professional you call should not just be adding more. Your unit will have a leak or another issue that needs to be resolved properly.

Adding more refrigerant will only make things worse and more difficult to deal with. 

Check The Air Filter

Filters should be changed frequently to ensure that airflow remains strong and constant.

If the filter becomes clogged, the air flow is reduced, which causes the AC unit to freeze up.

To change filters, you must first turn off the unit, then remove the front panel and the top cover.

Then you must find the filter box and replace the old one with the new one. When replacing the filter, make sure that you use fresh replacement filters.

Do not reuse them or else you risk contaminating the entire AC unit.

Changing air filters not only keeps the air clean, but it also improves the efficiency.

Having clean filters will also help prevent any ice from building up inside your AC unit.

This is because ice buildup reduces the ability of the unit to move heat around, making it harder to keep cool.

Overall, it’s recommended to change your air filters every three months or do.

Anyone with allergies or pets may wish to change filters even sooner.

Take A Look At The Vents

Take A Look At The Vents

Another place where leaks can occur is the vents. These are small holes on the outside of the house that release warm air to the outdoors.

They are necessary to ventilate the home during the summer when the temperatures are high.

But if these vents become blocked, it will cause the AC unit to overheat.

You might notice that the fan blades start spinning too fast, or that the AC unit runs constantly.

In either case, it’s best to check the vents and see if anything is blocking them.

Examine The Condensate Drain Line

The condensate drain line is another area that should be checked regularly.

It drains water droplets from the evaporator coil back into the suction side of the compressor.

Sometimes, the line dries out and allows moisture to accumulate in it. This can lead to corrosion and blockage.

It’s best to inspect it monthly to ensure that it does not become problematic.

The moisture that is taken from the air will be collected in the condensate drip tray.

This water can eventually begin to overflow if the system ever becomes clogged.

When this happens, there will be an increased amount of moisture in the system. If that happens, the evaporator coil can easily freeze up.

You should always check for any blockages in the drain line.

If you are uncertain of how, you can always call in a professional to do it for you and show you how. 

Check The Blower Fan

Blowers typically run continuously while the AC unit is running. If it stops working, it could mean that the blower motor has died.

It is possible to fix this by replacing the blower motor, but it is usually best left to a trained technician.

When a system’s blower fan has somehow gotten damaged, ice can quickly form.

When a fan breaks or becomes faulty, the system performance will drastically decrease, which can result in high energy bills. 

Unless you are knowledgeable and familiar with how these work, you should call in a professional.

Even knowing where to look can pose a challenge if you don’t know anything about AC units.

When a technician arrives, they should automatically check the fan motor’s condition and see how old it is.

They might also check the power source and test the rotation speed to figure out what the issue is.

What If I Still Can’t Find The Problem?

If you have worked your way through this list and still can’t seem to find the issue, you might need to call in the professionals.

With all the different components and areas of the unit, it is often difficult to pinpoint the exact problem.

When a technician is called in, they will take a look at everything to determine the root of the concern.

Once they have done so, they will make sure that the system works properly. 

Final Thoughts

Figuring out what’s freezing up your AC unit can be extremely frustrating. Especially if it happens in the heat of summer.

The good news is that most issues can be fixed fairly easily, and if you follow the steps listed above, you can avoid having to pay a lot of money to get your home cool again. 

As we said before, the first thing that a homeowner should do after noticing their air conditioning units freezes up is try to safely troubleshoot.

Doing this can save some time and resources.

Central air conditioners can be difficult to work with when you don’t have a good understanding of them, so it’s always recommended to do some research.

Things like a frozen coil, a dirty filter, or any other seemingly minor issue can cause a lot of problems.

Always check the condenser coil and the outdoor unit to see if you can pinpoint the difficulty.

If you don’t know what a dirty filter looks like in an air conditioning unit (see also ‘How To Clean Your Air Conditioner Filter In 5 Easy Steps’), you can still call the professionals for some help. 

If you feel that you have done everything you can and still cannot solve the problem, or even find it, give us a call.

We will get your concern fixed in no time, and you won’t have to suffer any longer than you need to.

Professionals should check to ensure there is adequate airflow, and so that there is no faulty motor. You will have your AC back in no time.

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By 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