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Can You Use an Air Conditioner Without a Filter?

Like most modern-day home appliances, air conditioners (AC) will work despite missing a part or two. And for AC units, this can include no air filter. But is it really a good idea to go without one?

You can use an air conditioner without a filter. However, running your AC for extended periods of time without a filter can damage the unit due to dirt and debris accumulation. The absence of a filter can also lower indoor air quality, leading to a harmful living or working environment. 

Let’s explore in a bit more detail how the absence of a filter can result in mechanical problems to your air conditioner, and how running one can maintain good air quality. Then, if you’re ready to pick out the perfect filter for your AC unit, we’ve included a quick and breezy guide to help you get started.

How a filter keeps an air conditioner healthy.

Think of a filter as a bouncer. Its main duty is to keep the riff-raff out of your AC unit.

It might not be pleasant to think about, but the air around us contains more than just oxygen and nitrogen. There are lots of tiny particles of dust, hair, and debris floating along with it! As you can imagine, we don’t want to be breathing that in – and neither does your air conditioner.

Can You Use an Air Conditioner Without a Filter

The filter’s job is to keep the clean air flowing in and the other stuff from building up inside your AC unit that can cause it to work poorly or even to break down.

Below are a few problems that can occur when you don’t have a filter doing its job.

Buildup of Gunk in Freon Tubes 

Most of the issues involving AC units are due to a buildup of gunk in the system, and this usually starts in the Freon tubes. 

An air conditioner works simply: it pulls air from your home and blows it along copper tubes that contain Freon. These tubes stay wet due to condensation in the air. As a result, if unfiltered air blows across the copper tubes, the icky stuff such as dirt and debris, will stick to the condensate and coat the compressor fins.

All this means is you’ll have one unhappy AC unit that has to work extra hard to push out clean, cool air to you.

Clogged Condensate Drain

If the Freon tubes are clogging up, you can bet the condensate drain is also feeling a bit full.

Can You Use an Air Conditioner Without a Filter?

As the condensate accumulates in the Freon tubing, it drips down into a small pan. This pan is then drained to the outside of your home. These drains don’t handle debris such as hair and dust very well, and if too much of it accumulates, clogging will occur.

The end result: an unhappy drain that will back up water and trip your AC unit to turn off until the problem is fixed. Or worse, water damage.

Moldy Ductwork

Whatever dirt and debris don’t stick to Freon tubes will no doubt end up stuck in your ductwork

With all this moisture building up in the ribbed aluminum tubes, this becomes the ideal place for mold to grow. As mold spores circulate throughout your home, it can cause serious health issues to you and your family.

How does a filter keep air clean?

Now that we’ve explored some of the more technical problems that can happen when running an air conditioner without a filter, let’s look at how having a filter can maintain and even improve indoor air quality.

As mentioned above, there is a lot of gunk floating around in the air. Particles of dust, hair, pet dander, and dirt are constantly wading through the invisible medium. For our own health, it is important that the indoor air we breathe is clean, so our lungs don’t get irritated or congested.

Can You Use an Air Conditioner Without a Filter?

Air filters work to clean the air by creating a barrier against debris. They act as a screen to capture these unwanted particles in the filter media as air flows through it. Basically, particles that are too big for the holes in the screen shall not pass.

For this reason, when you run an AC unit without a filter, nothing prevents that unpleasant gunk from being sucked through the intake and pumped back through the air vents and to you. Just by having a filter running with your air conditioner, you can greatly reduce the likelihood of breathing in dust, dirt, or debris within your home.

This is a good thing because poor indoor air quality can have negative impacts on your body. It can cause headaches, tiredness, sinus congestion, and can worsen pre-existing allergy or asthma symptoms.

How do you choose the right filter?

So now that you’ve been acquainted with the air filter and its remarkable skill set, it’s time to find your air conditioner a sidekick.

There are three basic factors to consider when choosing a filter. They are: 

  • Size
  • Shape
  • Material


Size undoubtedly matters when it comes to air filters, as it needs to fit inside your AC unit properly. In most cases, there will be an existing filter you can get the dimensions from, but if there isn’t one present, look for a manufacturer’s label and contact information. You might also be able to snap a picture and ask an expert at a local hardware store.

With that said, most filters for residential cooling are 1-inch thick though some houses do require up to 4-inch filters due to the volume of air circulating in the home.


Usually, the shape of a filter is pretty standard. However, there are adjustable filters for special ventilation openings. Nonstandard sizes and shapes of filters are also available for room air conditioners, register vents and return vents in the floors, walls, and ceilings.


You’d be surprised to know that there are various kinds of materials and styles of air filters to choose from. It is worth considering what you want to trap in your filter, as the performance is impacted by the size and density of the material. Depending on the type, a filter may be capable of capturing dust mite debris, mold spores, bacteria, pollen, and more. 

The least expensive filters have a layer of fibers (most often fiberglass). Pleated filters tend to be more efficient due to the pleats covering a greater surface area. Reusable filters are also an option. They are made of a material that can be easily cleaned with water. 

When to change a filter.

If you’ve already found an allstar filter for your air conditioner, it’s still important to remember to change them regularly.

Even the best of filters won’t perform well if it’s clogged with thick layers of particle gunk!

Can You Use an Air Conditioner Without a Filter?

The general guideline is to get a new filter every month. However, there is a bit of wiggle room depending on the filter and/or the type of living space.

Below is a list of average timeframes that may help you plan your next filter switch-out:

  • Single occupant and no pets or allergies: every 6-12 months
  • A suburban home without pets: every 90 days
  • One dog or cat: every 60 days
  • More than one pet or if anyone has allergies: 20-45 days


Using an air conditioner without an air filter, though doable, is not a good long term plan if you hope to keep your AC unit working properly for years and years. Dirt, debris, and dust can accumulate in areas such as Freon tubes, condensate drains, and ductwork, making it difficult for the system to continue to work effectively to cool your home.

Running an air conditioner without a filter can also have a detrimental impact on the quality of indoor air in your home. A filter’s job is to keep unwanted particles from circulating around your home, so if you go filter-less, you run the risk of breathing in dust, pollen, and debris, which can lead to certain health problems. 

Choosing a filter for your AC unit is simple. All you need is the size and shape information, which can usually be found on the pre-existing filter. You’ll also want to consider the material type, as some collect a wider size range of particles than others. 

To keep a filter working well, it is a good idea to change them out regularly. Timeframes can vary from one month to a year, depending on the type of filter you install. 


  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

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