The Consequences of Running Your AC Without a Filter: Risks, Impacts, and Solutions

If you think you can get away with running your AC without a filter, you may want to think twice. We understand in some cases you may forget to have one in place, however, this is a step that you want to avoid missing. If this is something that you think you can avoid, you could find yourself needing to repair many areas of your unit.

The longer you go without having a filter, the more problems you risk running into. If you run your AC unit without a filter, dirt and other debris can build up inside of your system. As a result, you will end up dealing with poor air quality inside your home.

Running your AC without a filter can cause issues such as condensation drain problems, poor air quality, Freon tube problems, and ductwork problems. Fortunately, these can be avoided when choosing the right type of filter and replacing it when needed. We’re going to go over some of the problems when running your unit without a filter, what the best type of filter is, and how to replace it. 

What Happens If You Run Your Ac Without a Filter?

Running your AC without a filter could lead to serious problems. It could cause condensation drain problems, poor air quality, Freon tube problems, and even ductwork problems. As you continue to read, we’re going to discuss these 4 problems in more detail.

Condensation Drain Problems

Believe it or not, condensation drains are one of the most overlooked areas of your AC. We know that ACs are used for cooling the home, but to properly regulate the humidity in your home, your AC needs condensation drain lines that work. A drain line is a small pipe that will move water and other types of debris from the condensation drain pan and will allow the condensation to move from the drain.

If you acquire too much dirt build-up in your condensation drain line, this can form a clog. Since your drain line is responsible for releasing moisture, a clog could cause mold to form, which could also be the reason for a clog. This is also why it’s very important to make sure you’re running your AC unit with a filter. 

As you know, filters are designed to catch small particles such as dirt and dust. Even though your unit can run without a filter, this would be an expensive cost when your condensation drain becomes damaged. Without an AC filter, this will cause your drain to go into failure, which will prevent it from releasing moisture from your AC.

When this occurs, you’ll be stuck with a build-up of condensation on the Freon tubing. Due to the build-up, the condensation will collect in the pan, which can cause problems for your entire system. While clogs are hard to prevent entirely, you can make sure that your AC unit has a filter and that it is changed regularly.

When you’re able to maintain your unit semi-annually, this will make a big difference in your condensation drain pipe. While performing your routine maintenance, make sure that other factors are checked such as the thermostat, refrigerant levels, and other pipes, as these are all linked to the condensation drain line.

Poor Air Quality

Over the years, researchers have figured out that small particles in the air can cause poor air quality in our homes. If you have a family, you know that this is a top concern when it comes to the health of your loved ones. Did you know that smaller particles can dive deeper into your lungs and bloodstream?

When it comes to your health, this is an important concern to have. The main reason your home may have poor air quality is due to not having a filter on your AC unit. If you don’t have a filter, you won’t get much filtration.

When you don’t have an air filter, you’re not only making your air quality worse, but this is also affecting your ducts, blower, AC, coil, and everything in between. Not having a filter will send all of these particles and other debris to fly around in your home. Even though health problems are the most obvious, this could also cause problems for your HVAC system and utility bills.

Having extra particles in your HVAC system will cause it to work harder, therefore increasing the risk of it breaking. This means that not having an air filter will slow down your airflow and spread more dirt and dust throughout your home. Another problem poor air quality causes is an increase in your utility bills.

Since your HVAC system will be working overtime from not having a filter, this will increase your utility bills. If you notice that your monthly utility bill has increased, it’s worth checking to see if you have a filter installed or if it needs to be replaced.

To improve your air quality without having a large expense, there are some ways you can approach this issue. You can check to see if your unit has a filter, check your ventilation for blockages, make sure humidity levels are stabilized and get a home purification device.

Freon Tube Problems

Freon tube problems will occur when your unfiltered air blows across wet tubes, allowing the dirt to stick to the blades. This will end up causing problems for your AC unit. Freon tubes operate by allowing Freon to travel through your ACs coils to help it cool down and convert your system back to low pressure. Not having a filter on your AC can cause airflow obstruction.

Removing any blockages that have occurred in your Freon tube can prevent any ice buildup. To have an AC that runs at full capacity, your Freon tubes must run efficiently. These tubes can not run efficiently if they are blocked or covered in dirt.

Without an AC filter, you will notice water collection that will allow the dirt to attach itself. With dirt coating the Freon tube, this will eventually become an expensive cost if not fixed properly. To fix this problem, the first thing you’ll want to do is make sure you have cleaned up any water and dirt buildup on the inside.

Once your water and dirt buildup has been cleaned, install your air filter. We understand that you may forget to replace your filter, but please be aware that this is the key component of a properly-functioning unit.

Ductwork Problems

You will notice that if your AC unit does not have a filter, you may run into ductwork problems. Any dirt that you notice passing through your Freon tubes will make its way to your ductwork where it will become trapped. When this occurs, this may allow mold growth from the environment being damp.

If mold begins to grow in your ductwork, this will introduce health problems for you and your family. If you fail to put a filter in your unit, this will cause improper airflow throughout your home. Without a filter, there is no way for your unit to collect the dirt particles that pass through, which over time will lead to a buildup in your ductwork.

To fix this problem, you should check to see if there are any clogs or leaks from this occurring. The first thing you’ll need to do is check your air vents to see how the airflow is from one vent to another. If you notice the airflow has been reduced, you may have a clog in one of the ducts from dirt.

To avoid any additional issues with your ductwork, make sure you have an AC filter in place. You should change your filters monthly or quarterly when needed to keep your unit working efficiently. If you notice that your filters are clogging at an alarming rate, this could be due to an excessive amount of debris buildup in your ductwork.

How Can You Change Your AC Filter?

If it’s time for you to change your AC filter, while you need to pick the appropriate filter for your unit, you’ll also need the right materials or tools to put one in. A few things you’ll want to make sure you have on hand are a tape measure or ruler, your AC manual, and the new AC filter. As you continue to read, we’ll go into more detail about the different types of filters, their sizes, how to choose the right one and to properly replace your current filter. 

Step 1: Pick the Right Filter

When the time comes back around to replace your air filter, you’ll need to make sure that you are choosing the right one for your unit. Did you know that air filters come in different types and sizes? Trying to pick the right filter size may seem like a difficult task, however with a guide, you can obtain the correct measurement for an easy installation.

AC Filter Sizes

AC filters have labeled parts with 3-part dimensions. When you read the measurements you’ll see its length, width, and its depth. Here are a few common AC filter sizes below:

  • 18 x 30 x 1”
  • 16 x 24 x 1”
  • 10 x 20 x 1”

Finding the right filter size is an easier task than it may seem. The most important thing you’ll want to make sure you do is to get the current measurements so you’re not getting the wrong size. If your filter is fitting snugly, replace your filter as recommended by the manufacturer.

If you need to take manual measurements, make sure you’re rounding to the closest inch to obtain the nominal filter size. Changing your AC filter is just one important component of having your AC unit run efficiently.

Types of AC Filters

The main difference between the different types of air filters is their ability to filter pollutants in your home. This would depend on the type of material and the layout that is used. Here are a few different types of filters that you’ll be able to choose from.

1. Fiberglass Air Filters: Fiberglass filters are flat-paneled filters that are held together by a metal grate. This filter is one of the most common AC filters because of how affordable they are. If you’re on a budget, you might want to consider this one.

Fiberglass Air Filters

Even though these filters are affordable, they don’t do much when it comes to improving your air quality. Fiberglass air filters only filter around twenty percent of particles that include dust, fibers in carpets, and pollen.

2. HEPA Filters: HEPA filters are considered high-efficiency filters and one of the best filters you’ll have to choose from. They can remove up to 99% of pollutants in your home including dust, mold, pet dander, bacteria, and smoke particles. Many people who have allergies and respiratory problems prefer this filter.

While this filter is the best, you must also know that it is more expensive than the others. If you’re on a budget, you may still want to keep your options open for something more affordable.

3. Electrostatic Filters: These filters perform just the way the name suggests. The static of the magnet will trap pollutants on the filter screen. Since this prevents allergens in your home, these filters are ideal if you’re suffering from allergies.

Electrostatic Filters:

For improved efficiency, you will notice that these filters will also have a carbon filter. These filters will be flat-paneled or pleated and also come in both washable and disposable options.

4. UV Light Filters: Another option you’ll have to choose from are UV light filters. These filters use UV lights to kill bacteria and viruses. These filters are perfect if you’re looking to rid your home of things like mold spores.

UV Light Filters

Even though these filters do remove bacteria and viruses, they do very little to remove the dust from your home. If you’re shooting to remove dust particles from your home, you may want to go with another option.

How to Choose the Right AC Filter

There are plenty of factors you’ll need to take into consideration when choosing the right AC filter. If you’re a person who suffers from allergies, has pets, or opens your windows often, you’ll want to get a filter that has a higher MERV rating.

If you’re a person who just wants to block out particles and other debris, then you can buy a more affordable air filter. Filters that have a higher MERV rating are often used in hospitals to improve sickness.

Step 2: Replace the Filter

Replacing your air filter is easier than it may seem. The first thing you’ll want to do is locate where your filter is located. This could be in the return air duct which pulls air from your room back into the handler system. If your unit shares a heating and cooling system, your filter is probably located near the blower system.

Next, you’ll want to ensure you have the right type of filter and the right size. You want a filter that not only keeps particles out of the air but will help improve the air quality in your home. Once this is completed, turn off the power to your unit so no dirt or other debris can get sucked in.

You’ll then want to slide the old filter out of the slot and check the condition of your unit. This is to ensure that you don’t have any clogs. Dispose of your old filter safely by putting them in a plastic bag and throwing it straight into the trash bin.

Finally, you’ll want to insert your new filter by following the arrows on the frame to show you the direction that air needs to flow through the filter. When inserting your filter, ensure that the arrows point opposite from the return and towards the handler. Since you know how to replace your filter, don’t forget to set your monthly or quarterly reminder to replace it with a new one.


In conclusion, having an AC filter in place can help you avoid issues such as condensation drain problems, poor air quality, Freon tube problems, and ductwork problems. The best type of filter to have in your unit is a HEPA filter.

Tip: to have an AC unit that runs efficiently, you should make sure you’re replacing your filter monthly or quarterly depending on the model.