Everything You Need To Know About Cabin Air Filters And How To Replace It

The world may be on fire, but you don’t have to breathe it in. 

A very dirty in cabin air filter.
Jonathon Klein

The world is, quite literally, on fire. The wildfires of the American West are precursors to more fires each and every year. We must face that new normal. And even though we’ve made some strides to curb air pollution, carbon dioxide emissions still threaten our future. This type of blanketing intruder can be difficult to avoid, but your car’s interior can be a sanctuary from the fumes thanks to your cabin air filter. 

While your car’s engine-feeding air filter screens the air entering the combustion cycle, a vehicle’s cabin air filter strains the air you breathe inside your ride. Think of cabin air filters as gas masks, keeping the pollution, smoke, and that bro-dozer’s disgusting coal-rolling out of your lungs and out of the hospital for acute asthma, bronchitis, and other respiratory diseases. 

Jonathon Klein

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During this era of environmental instability, you might be wondering how cabin air filters work and if yours is good. You might also be curious about how long they last, what affects them, how much they filter out, and how to replace them. Well, fine reader, have we got the guide for you! We’re going to discuss all of that, including a few questions you might not have thought about. 

So, sit back, grab a canned air, and follow along as The Drive’s crack info team teaches you everything you ever wanted to know about cabin air filters.

What Is a Cabin Air Filter and How Does It Work?

A cabin air filter is a flat, pleated, typically rectangular cartridge made of a framed combination of paper, mesh, and/or cotton that contains activated charcoal. As air is sucked into your car’s cabin, cabin air filters trap airborne contaminants and debris before it enters your personal space. They are usually housed behind your glovebox or at the base of your car’s windshield, underneath the hood. 

Cabin air filters are designed to remove 99.995 percent of airborne contaminants down to 0.1-0.3 microns—a micron is 1/25,000th of an inch and is used to measure the size of particulates in the air. Essentially, they keep your lungs from breathing in pollution, wildfire/forest fire smoke, cow farts, your friend’s farts, skunks, and other things you don’t want to smell or let into your lungs.

Signs of a Dirty Cabin Air Filter

The signs of a dirty cabin air filter are pretty easy to detect, that is unless you lack the sense of smell. Here are the most common ways to determine if your cabin air filter needs replacing.

You Smell Odors or the World Outside

The easiest sign of a dirty cabin air filter is the scent of something outside of the car, such as wildfire smoke, cow pastures, or skunks even when you have the HVAC system on recirculate.

You See Particulates or Smoke 

Clearly, there’s an issue if you see smoke or other particulates coming in through your car’s vents. This may also indicate your cabin air filter has a tear, rip, or break and needs to be replaced immediately.

Poor Air Flow

When a cabin air filter becomes clogged due to years of neglect, your car’s HVAC system may not be able to blow as vigorously as it did when new. It might feel as if you have an old Italian supercar, the A/C feeling like it was being blown through a straw by an asthmatic. Not good, Cotton. 

You Can Hear The HVAC Struggling to Push Air Out

Likewise, you might hear the HVAC mechanism struggling to push the air through the car. It might sound louder than usual or as if something were blocking a vent. 

What Happens When Your Cabin Air Filter is Dirty?

You get all the above signs of a dirty cabin air filter. And if you’re there, you’re either stuck breathing in your own eggy farts or, far worse, you’re breathing in the toxic pollution of a city’s emissions or the pea-soup-thick smoke from your residence’s wildfires. 

Neither is good, as one doctor in San Francisco compares breathing in wildfire/forest fire smoke to “smoking eight cigarettes.”

How To Replace Your Cabin Air Filter

With all that information now at the forefront of your mind, especially for those experiencing wildfires and forest fires around the world, you’re probably wondering how to replace your cabin air filter. Stuff your worries in a sack, because The Drive’s info nerds have you covered. Let’s do this!

Everything You Need To Replace a Cabin Air Filter

We’re not psychic, nor are we snooping through your toolbox or garage, so here’s exactly what you’ll need to get the job done.

Tools List

  • You, you’re the tool. 
  • Flathead screwdriver/Torx/Hex wrench (maybe)

Parts List

Jonathon Klein

The location of the author's cabin air filter.

How To Replace a Cabin Air Filter

Now let’s get down to the nitty-gritty details on how to replace your cabin air filter. 

Jonathon Klein

The underside panel I needed to remove. 

Replacing In-Cabin Air Filter

  1. Remove the contents of your glove box if you have to. The author's Volvo doesn't require that, just a few Torx screws beneath the glovebox.
  2. Remove the glove box door from its hinges if needed.
  3. Remove any panels in the way. 
Jonathon Klein

Ew. 

4. Remove the old, stinky, smoke-saturated air filter from its slot. 

5. Replace it with a new cabin air filter.

6. Reattach the glove box door and replace its contents if needed. Don’t forget your insurance, registration, and that old takeout menu from Paul’s House of Deep Dish Pies you’re definitely saving for your next breakup (or simply next Monday). 

You’re done!

Replacing an Underhood Cabin Air Filter

  1. Start the car and turn the windshield wipers on. Turn the car off when the windshield wipers are pointing toward the roof of the car. If your car has a windshield wiper service position, hit that button. 
  2. Pop the hood.
  3. Remove the windshield washer hose from the clips on the plastic cover near the base of the windshield.
  4. Pull away the hood weatherstripping.
  5. Remove the plastic cover (you may need a flathead screwdriver).
  6. Remove the cabin air filter.
  7. Replace with the new cabin air filter.
  8. Reinstall the plastic cover, hood weatherstripping, and windshield washer hose.
  9. Close the hood.

You’re done, congrats! 

Tesla Model X with its falcon doors up.
Tesla

Tesla Model X with its falcon doors up.

Factors That Affect Your Cabin Air Filter's Longevity 

Life is full of variables that positively and negatively affect your health. Cabin air filters are no different. Here are a handful of external and internal variables that can affect your cabin air filter’s life and effectiveness.

Cigarette, cigar, and marijuana (please don’t do that in your car) smoke can all affect the effectiveness of your cabin air filter. As you smoke more in the car, the filter becomes further clogged by your particular habits. Likewise, those who use hair spray or other beauty spray products can also impact the health of your cabin air filter. 

If you live in an area where wildfires are prevalent, you’ll want to replace your cabin air filters every year. Cabin air filters are designed to filter out 98-99.995 percent of airborne particulates down to 0.1-0.3 microns. Wildfire/forest fire smoke ranges between 0.4-0.7 microns according to the EPA

Can Your Window Seals Affect Your Car’s Air Quality?

They can! If your window seals have become cracked or are off their guides, outside air—and everything that goes along with it—can enter your cabin and affect your air quality. Maintaining your seals allows your HVAC system to properly recirculate the clean air without any extraneous pollutants entering your car.

How Does A/C Recirculation Work and Affect Your Cabin Air Filter?

Your car’s air conditioning recirculation setting is one of the most important tools in combating airborne pollutants. By selecting recirculate, you make your car as close to a closed-loop system, where the majority of outside pollutants never enter the car, as possible without having NASA-grade air scrubbers. This is especially handy with forest fires/wildfires where smoke is cut off from the cabin. 

FAQs About Cabin Air Filters

You’ve got questions, The Drive has answers!

Q. How Much Does It Cost to Replace Your Cabin Air Filter?

A. Most cabin air filters cost about $15-$30 depending on the level of filtration and your vehicle’s make and model. Some can cost more, and you’ll also pay more if you have a professional replace it.

Q. Do I Really Need to Replace My Cabin Air Filter?

A. Yes, you absolutely do. Without it, you’re breathing in the world’s pollution and filth. Do you want to breathe in the world’s grossness? We didn’t think so. 

Q. How Often Should I Replace My Cabin Air Filter?

A. Most manufacturers say you should replace your cabin air filter every 15,000-30,000 miles. However, if you live in a place where forest fires/wildfires or pollution runs rampant, you’ll want to replace it yearly or even sooner.

Q. How Do You Filter Out Forest Fire Smoke?

A. By replacing your cabin air filter and turning your HVAC system onto “Recirculate.” That’s the little button on your dash that looks like a look with an arrow.

Q. What Does Tesla’s Bioweapon Defense Mode Do?

A. According to Tesla, the brand’s Bioweapon Defense Mode was “developed a HEPA filtration system capable of stripping the outside air of pollen, bacteria, and pollution before they enter the cabin and systematically scrubbing the air inside the cabin to eliminate any trace of these particles. The end result is a filtration system hundreds of times more efficient than standard automotive filters, capable of providing the driver and her passengers with the best possible cabin air quality no matter what is happening in the environment around them.”

Essentially, it’s a cabin air filter on steroids.

Q. How Long Does Tesla’s HEPA Filter Last?

A. Tesla claims it will last up to three years. 

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