When and How to Replace Your Cabin Air Filter

engine air filter
The Cabin Air Filter Helps You Breathe Better, Like an Engine Air Filter Helps Your Engine Breathe. http://www.gettyimages.com/license/487563886

The engine air filter first featured on the 1915 Packard Twin Six. Over two decades later, the 1938 Nash Ambassador featured the first cabin air filter, but several decades passed before modern luxury cars featured them. Today, many economy and mid-range automobiles also offer cabin air filters. What does the cabin air filter do? How long does the cabin filter last? How do you replace the cabin air filter?

The engine air filter keeps dust and contaminants from getting into the engine, where it accelerates wear and forms performance-robbing deposits. Similarly, the cabin air filter prevents dust and pollen from getting into the passenger compartment, where it can cause all manner of performance-robbing effects on the driver and passengers. Just ask anyone who suffers from allergies.

Just as the engine needs to breath clean air, so do we, which is why our noses and throats have built-in filters to keep out most of whatever’s floating around in the air. Still, those who suffer from allergies know that nose hairs and mucus don’t cut it, especially when driving through several zones of airborne pollutants, such as pollen, dust, dirt, and soot. The road is also a smelly place, for which certain cabin air filters are well-suited.

Why is Cabin Air Filtration Important?

a woman sneezing, possibly due to allergies
Cabin Air Filters Eliminate Many Common Allergens Before You Breathe Them In. https://pxhere.com/en/photo/891702

The “cabin air filter” may be referred to as “air conditioner filter,” “dust filter,” or “cabin filter,” but they are not HEPA (High Efficiency Particulate Air) filters, which are tested to remove over 99.97% of particles down to 0.3 µm. The cabin filter is a paper or textile filter medium, fitted to strain out airborne contaminants before they enter the cabin. Most cabin air filters are strictly filtration mediums, but some feature odor-eliminating properties.

  • Basic cabin filters, or particulate cabin air filters, depending on the brand, can filter out up to 99% of contaminants over 3 µm in size, including PM10, dust, ash, pollen, spores, hair, feathers, leaves, and insects. Some filters can filter out over 95% of particles between 1 µm and 3 µm in size, such as bacteria, some viruses, finer dust and soot, and dangerous PM2.5, produced by vehicles of every size.
  • Carbon cabin air filters have all the same filtration properties of basic filters, but with the added benefit of odor elimination. A layer of activated charcoal is sandwiched between successive paper or textile filter medium. The charcoal medium absorbs exhaust fumes and unpleasant odors, improving air quality even more than particulate filters.

Aside from allergic reactions, which can impair the driver, some contaminants are known to cause serious health problems. The World Health Organization (WHO) has linked PM10 and PM2.5 (particulate matter less than 10 µm or 2.5 µm) to increased incidence of asthma, lung cancer, respiratory disease, cardiovascular disease, to name a few.

Particulate cabin filters are less expensive than carbon cabin filters, but the extra expense may be justified if you regularly drive in stop-and-go traffic, through industrial areas, or are concerned about food or pet odors.

How Often Should the Cabin Filter be Changed?

comparing new and old cabin air filters
Usually, a Visual Inspection is the Best Way to See if the Cabin Air Filter Needs Replacing. https://www.flickr.com/photos/ryangsell/10789771066

Automakers and technicians may suggest replacing the cabin air filter once or twice a year, or depending on mileage, but there are several factors that can affect the lifespan of an individual cabin filter.

  • Mileage: Generally, the more a car is driven, the more air a cabin air filter will process, so mileage can be a pretty good indicator of when to replace it.
  • Time: Somewhat less important is how long the filter has been in service. Particulate filters don’t degrade over time, but carbon filters continue to absorb odors from the moment they are unsealed.
  • AreaSome areas are dustier than others, and other areas have higher pollen counts. The more contaminants there are in the air, the less time the cabin filter will last.
  • Season: Many airborne contaminants are greater at certain times of the year. Dust, mold, and pollen levels vary throughout the year.

The best way to determine when to replace the cabin air filter is either by visual inspection, olfactory inspection, or by noting how much airflow is being impacted. Fortunately, most modern cabin air filters are easily-accessible, so a five-minute inspection should give you a good idea of filter lifespan. Replace the filter if it’s filled up, smells bad, or is restricting airflow.

How to Replace the Cabin Air Filter

cabin air filter behind the windshield cowling
This Cabin Air Filter is Accessed by Pulling Off a Windshield Cowl Panel. https://www.flickr.com/photos/55744587@N00/10855059423/

The cabin air filter is positioned so it can process air going into the air conditioner, but accessing depends on the vehicle. The most common cabin filter access point is located behind the glove box on the passenger side. Less-commonly, the filter is accessed through the engine compartment behind the windshield cowling. Even less-common are other locations, such as behind the center console kick panel, as in older Lexus sedans, but check your owner’s manual for specific location of the cabin air filter and how to replace it.

To access the cabin air filter, you may not need any tools, though some vehicles may require some basic hand tools, such as a nut driver or Philips or flat-head screwdriver.

  • To replace the cabin air filter, simply remove the glove box, kick panel, or cowl cover.
  • Then, remove the cabin filter cover, usually held in place by tabs or screws.
  • Slide out the old cabin air filter. You can use a vacuum to prevent captured particles, insects, or leaves from getting through the rest of the system.
  • Install the new cabin air filter, noting correct airflow direction, usually indicated by an arrow. Most flow to the rear of the vehicle or down toward the floor.
  • Install the cabin filter cover, then the glove box, kick panel, or cowl cover.

After replacing the cabin filter, enjoy a few more months of driving in clean air, even when the outside air isn’t.