How Important are AC Filters?

ac filters

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You are likely aware of some of the more essential parts of aircon in a car, such as a compressor, fan, and chemical refrigerant. One of the products that cause frequent debates among experts is the AC filter. Is it necessary for you to have in your car? How often must you replace it? Below, we have the definitive guide to the question, “How important are AC filters?”

What is an AC Filter?

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An AC filter, otherwise known as a cabin air filter, is a part of the aircon system in your car. The feature is more recent and is only typically seen in later-model vehicles manufactured after 2000. According to, the filter helps purify the air that comes into a car, catching pollen, dust, and other airborne materials. It can clean any air that comes into the car from a variety of sources, including the:

  • Heating System
  • Air Conditioning System
  • Ventilation System

Your manufacturer should provide you with a guideline as to when to replace parts of aircon, including the AC filter. A low-end estimate indicates that filters can last between 12,000 and 15,000 miles. However, as designs have evolved, some manufacturers install filters that can last up to 20,000 miles. The maintenance schedule in your owner’s manual should instruct you when to replace the filter. 

It’s also worth noting that the location where you drive, and the frequency in which you do so, could have a significant impact on the longevity of your filter. For instance, those who operate in polluted urban areas will likely need to replace their filter more often than someone who lives in an area with better air quality. Drivers in dusty or sandy areas may need to replace their filter often too. 

Is the AC Filter Important?

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Many people often wonder if the AC filter is a critical part of the aircon system. The belief is that if cars of the past did not need the screen, why would they need them in modern cars? Thanks to advanced research, we now know that failure to keep the AC filter clean could result in drivers and passengers inhaling dangerous smog and exhaust from other cars. So, yes, the AC filter is vital. An excellent analogy would be comparing the AC filter to the engine air filter. The engine air filter exists so that you can keep debris from entering your engine, where it could cause severe problems. The engine air filter allows your engine to “breathe” air that is pure. The AC filter does the same thing, except instead cleaning the air for the engine, it cleans it for you and other passengers in the cabin.

So, ask yourself this. Do you replace your engine air filter regularly? Odds are, the answer is yes. If so, then you should replace your AC filter regularly as well. And if you don’t change your engine filter regularly, then we are gravely worried about the status of your car! We recommend visiting your local mechanic as soon as possible. Tom Potter, a mechanic in Virginia, spoke with Angie’s List about AC filters. He said, “The cabin air filter is kind of out of sight, out of mind. If you tell someone that they need their cabin air filter changed, some say, ‘What is that?’ They think you’re talking about the engine air filter. I’ve seen people go 90,000 miles without changing it because they didn’t know they needed to.”

He continued to say that the filters can benefit those who suffer from allergies because they prevent pollen from entering the car. However, the AC filter is about more than just air quality. The screen can also play an integral role in your car’s air conditioning system. Phoenix-based mechanic Troy Roberts said, “When the air is dirty, the A/C will work harder, and the motor can burn up.” Failure to replace the filter could result in less air coming through your vents. Your system will then work harder to in an attempt to keep the car cool. 

A dirty filter would also result in the air that does come through the vents being less cold than it would with a clean screen. Some users find that parking the car provides temporary relief from this, but as soon as they begin driving the problem starts again. This is because air passes through the AC filter to another part of your aircon system, the AC evaporator. The evaporator exists to cool the air, operating at freezing temperatures. The evaporator also prevents ice from building up within the aircon system. When air cannot flow through the filter, ice will begin to build, and your air conditioning system will no longer keep you cool.

When Should You Replace Your Filter?

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You should at least consider replacing your filter when your manufacturer tells you too. Be sure to check your owner’s manual for more information about the AC filter and other parts of the aircon system. Following your manufacturer’s recommendations is an excellent way to help keep your car healthy and ensure your aircon system functions properly. However, if you drive your car frequently or drive it in areas with poor air quality, you may need to replace your filter more often than recommended by your manufacturer. Fortunately, there are some warning signs for which you can be on the lookout that could potentially indicate a clogged filter. We described the first telltale sign, diminished cooling airflow, in the section above.

Additionally, another sign is a loud noise when the fans of your AC unit are blowing. You’ll likely notice this most whenever you turn the fans high. Another indication of a poor AC filter would be if you smelt a lot of bad odors in your car. While some bad odors are inevitable, if you find that you smell them more often or that the smell has grown more pungent, you may need a new filter. The best course of action, especially if you have not changed your AC filter in a while, is to visit your trusted local mechanic. A mechanic can evaluate the parts of your aircon system to determine the primary cause of the problem. They can also remove your AC filter to determine how dirty it is and if you’ll need to buy a replacement. 

How to Replace the Filter?

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If you would prefer to replace your filter rather than go to a mechanic, there are a few steps you’ll first need to go through. First, and arguably most critical, you’ll need to pinpoint the filter’s location. The cabin air filter in most cars is behind the glove box. Many car owners find that they can reach the screen by releasing the fasteners to the glove box. If you are unsure about how to release your glove box or feel as though your cabin air filter is not there, you can consult your owner’s manual. The owner’s manual should give you explicit directions to describing how you can replace the equipment. If your filter is not behind the glove box, it will likely be under the dashboard or hood.

Once you’ve found your filter, you can evaluate whether it needs replacing and, if so, the model you need. ​Cabin AC filters are not the same, so it’s imperative that you find one best suited for your vehicle. If your screen is underneath the dashboard or hood, you can expect to pay a bit more than if it were behind the glove box. However, completing the process on your own should help save money. The filter can typically cost depending on which type you purchase. However, some mechanics will charge two to three times as much for labor. By replacing the filter on your own, you’re cutting out substantial labor costs, which will save you a significant amount of money in the long run. Spending time learning how to replace the filter could pay dividends in the future.

In regards to replacing the filter on your own, Potter said, “Some (filters) are quite a chore. Clips and pins that need to be taken off, and if you don’t know whatyou’re doing, you can break it when you pull it out. But generally speaking, it’s an accessible part.” This demonstrates that while it may take some initial investigate work, finding the filter could eventually be worth your while.

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We recommend that you check the air filter at least once per year. Also pay attention to your odometer, as driving more frequently could cause you to need to replace your filter sooner than anticipated. Perhaps set six-month reminders in your calendar. For both your health and the performance of your vehicle, it’s better that you are diligent about checking the filter than not.

Furthermore, if you were to take your car to the dealership, you should ask them to see the filter before they throw it away. We’re willing to bet that you’re shocked at what’s in the filter. You’ll see everything from twigs to pollen. Seeing the screen will give you a better idea of what a dirty filter looks like so that you can hold your mechanic accountable or replace your own in the future.

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