Do Central Air Conditioners Have Filters? [And How To Maintain Them]

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Central air conditioners are fantastic for controlling the temperature in your home. However, sometimes it can be challenging to find the air filter. This can make you wonder if your conditioner even has a filter. We have researched if your central air conditioner has a filter and how to maintain it.

Yes, central air conditioners have filters. It is extremely common for a central air system to have at least two filters. 

Maintaining your filters is pretty simple. All you need to do is clean or replace the filter every 45 to 90 days. Factors such as how much you are using your unit and whether or not you have pets can affect how often you have to change it.

Now that you know your AC unit does have a filter, we will discuss how to find that filter, clean it, and replace it. In addition to those topics, we will also cover how a dirty filter affects your unit, if you can run your AC without a filter, and if a two-inch filter is better than a one-inch.

Ceiling mounted central air conditioning system, Do Central Air Conditioners Have Filters? [And How To Maintain Them]

Do Central Air Conditioners Have Filters?

Yes, your central air conditioner has a filter. In fact, most central AC units have two or more filters. These filters clean the air and ensure good air quality as your unit circulates between inside and outside air.

Central air conditioner filters often are made of fiberglass or pleated materials. In older systems, it is more common to find cheaper, thinner one-inch fiberglass filters, while newer systems typically use thicker, pleated filters.

Removing Dirty Air filter for home central air conditioning system

Where Is The Air Filter On A Central Air Conditioner?

Before we cover how to replace the filter, you must know how to locate your filter. Different units have slightly different locations, so the fastest way to figure out where it is is to consult your unit's manufacturer's instructions. Indoor and outdoor units have slightly different locations.

Outdoor Unit Filter Locations

It is common for the filters in an outdoor unit to be located along the return duct. The filter may also be found in a wall, ceiling, or in the unit itself if it isn't there.

This vent will be larger than the air vents but vary widely in size. If you are unsure if a vent is a return vent, you can hold a piece of paper to it while it is on. Return vents will pull the paper toward them.

Indoor Unit Filter Locations

It is common for indoor units to have two or more filters. To change these filters, look for a slot near the air handler. The air handler is the box that holds the parts of your unit and is usually in the attic or basement.

If you cannot locate your air filter, you can always call a professional and ask. They will either come to your home and replace the filter or explain how you can do it over the phone.

How Do I Change My Central Air Conditioner Filter?

After you locate your filter, you can change it. Before you change it, ensure you have the correct size for your filter. The previous filter should say on it what size it is. However, if it doesn't, you can find the size by measuring the old filter's height and width.

When you change your filter, make sure that your air conditioner is off. If it is on your ceiling, make sure your ladder is level before using it.

Next, open your filter grill and remove the filter. Then, take your new filter, ensuring the arrow is facing up before placing it where the old filter was. You may want to vacuum around where the old filter was if it is dusty. Interstate HVAC has a video that illustrates how to do this:

How To Clean A Reusable Filter

Some filters are reusable and will need to be cleaned before being put back. To clean your filter, simply rinse it with water. You can also use a brush and mild detergent to get off stuck-on particles.

Once it is clean, shake off the excess water. It can be placed back in the system before it is completely dry because the system's airflow will dry it the rest of the way.

How Often Should You Change Your AC Filter?

Clean Air filter for home central air conditioning system

How often you should change your air filter depends on several factors. Some of these factors are what type of filter you have, house size, air quality, number of pets in the home, how often you use your unit, and if you or anyone in your family has allergies or certain medical conditions

On average, it is recommended that you change your filters at least every 45 to 90 days. Depending on the type of filter you have, six months is the longest you should go without replacing or cleaning your filter.

Filter Type

Disposable filters are often made of fiberglass or are pleated. Fiberglass filters are usually a cheap option but need to be replaced every month. However, if you have pleated air filters, you won't have to change the filter for at least three months, and sometimes up to six months if they are high-quality.

Washable filters are usually made of metal. They do not pick up as much dirt or fine particles as disposable filters do. However, washable filters need to be cleaned once every 30 days to prevent airflow blockage.

Home Size

If you have a bigger home, then you will need to change your filters more often. This is because the bigger your home, the more air the filter has to filter through.

Air Quality

There is usually less pollution in the air for people living in the country, and therefore less to filter. However, if you live in a city or somewhere affected by wildfire pollution, you will want to increase the number of times you change your filter.


Group of pets posing around a border collie; dog, cat, ferret, rabbit, bird, fish, rodent

When you have pets, they increase the amount of hair and dander in the air. As a result, your filter works harder. The harder it works, the more often it needs to be changed.

According to Energy Air, you should change your filter every 60 days if you have one pet. For each added pet, you can expect to get 3o fewer days of use out of your filter. In households with many pets, you might benefit from changing your filters as often as every 20 days.

Air Condition Usage

Obviously, the more you use your unit, the more often it needs to be changed. This means that you will change it more often during the heat of summer than you will during the winter.

Allergies And Other Medical Conditions

For people who have allergies and respiratory illnesses, changing your filter often is essential to helping control flareups and minimize symptoms. To avoid the build-up of allergens, replace your filter every 30 to 45 days.

Is A 2-inch Filter Better Than A 1-inch?

Filters come in many different sizes. Make sure you know what size fits your unit by reading your manufacturer's directions or measuring your current filter.

A 2-inch filter is thicker than a 1-inch filter. It has twice the surface area of the 1-inch filter.  As a result, it will work better and last longer. You can use the thickest filter your system will fit.

One-inch filters usually fit in the return vent, and thicker filters will fit in the air handler. So, the 2-inch is better at filtering than the 1-inch. However, do not use the 2-inch if your unit is only built for the 1-inch because it will not filter properly.

What Happens If You Run Your AC Without A Filter?

Sometimes you might not have any filters on hand and wonder if you can run your AC without a filter. It is crucial that you do not do this. Running your air conditioner without a filter can cause a lot of problems.

White Mechanical, Inc says that it can cause condensation drain problems, decrease your air quality, cause freon tube problems, and potentially cause mold or water damage problems in your ductwork. All of these problems can cause your system to have issues running and potentially create a health problem for you when mildew and mold build-up.

Can A Dirty Filter Cause AC Not To Cool?

Before closing this post, we wanted to quickly explain why it's essential to clean your filters regularly. Aside from lowering the air quality in your home and potentially causing health issues, it can also result in your AC being less able to cool and potentially cause damage to your system.

One of the first signs your filter needs cleaning is when your system is not cooling as well or evenly. This is because as particles build up on your filter, airflow becomes poorer.

This cold air becomes trapped and can freeze the coils on your machine. Once this happens, it can render the device inoperable, and you will need a professional to service your system.

Final Thoughts

Ceiling mounted central air conditioning system, Do Central Air Conditioners Have Filters? [And How To Maintain Them]

So, despite being difficult to locate, central air conditioners do have filters. It is vital to change this filter regularly to keep your system running at maximum efficiency. For best results, change your filter every 45 to 90 days, unless you have allergies, pets, or other factors that increase this number.

If you found this article helpful, be sure to check out these other posts on this blog!

Can You Pour Hot Water On A Frozen Air Conditioner?

How Long Does It Take for a Central AC to Defrost?

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