What is a cabin air filter?
Since the late 1990’s more and more vehicles have come equipped with cabin air filters. In 2017, it’s very difficult to find a vehicle that doesn’t come with one — even on a base model!
Much like an engine air filter filters the air going into the engine, a cabin air filter filters the air that gets used by the climate control system on a vehicle — the air the drivers and passengers breathe when inside the vehicle. Cabin air filters can come in 2 primary styles: a dust/pollen filter that traps particles in the air, and a charcoal media filter, which in addition to trapping particles in the air also helps reduce unpleasant odors from outside of the vehicle. A dust/pollen filter can be found on most modern vehicles, while a charcoal filter is usually found on higher end vehicles. Most vehicles with dust/pollen filters can upgrade to a charcoal filter if desired.
Why is it important?
Having a cabin air filter in place can reduce airborne particles from entering the vehicle. It is especially helpful to people with common allergies, and is designed to trap dust and pollen in the filter media. Charcoal media filters can additionally reduce unpleasant odors from outside the vehicle, such as exhaust fumes, cigarette smoke, and other foul smells.
What can go wrong?
A plethora of things can commonly impact a cabin air filter, but the biggest item is routine maintenance. This filter is designed to be changed every other year, or between 15,000 and 20,000 miles depending on the vehicle manufacturer. Every time the fan, heater, or air conditioning is active in the vehicle, the cabin air filter is hard at work, and can quickly become saturated with particles from the air. Some climates will require replacement of this filter far more often that specified by the manufacturer, especially if there is lots of dust, pollen, or dirt in the air. Additionally, people who park under trees generally find more leaves and tree debris in their filters than those who don’t park under trees.
Aside from routine maintenance, is is common in areas with high rodent concentrations for mice and rats to find their way into the fresh air intake duct, and make a home near or in the filter media. This sometimes has ramifications beyond simple filter replacement, but if applicable, the filter media should be inspected for signs of rodent infestation during changing. If a strong foul smell is present, the filter should also be inspected for remains of rodents.
Other small critters occasionally find their way into the fresh air intake, and make their home in or around the cabin air filter. This author once found a bird nest, and an ample supply of bird seed that had completely restricted the airflow of the filter, for example.
Lastly, delay in changing the cabin air filter, or a large amount of biomass saturating the filter media can lead to unpleasant odors. If you notice an abnormal smell, changing the filter and performing a fresh air intake treatment can be necessary.
How do I know if it needs to be replaced?
The most common symptoms that suggest the cabin air filter needs attention are foul smells, and restricted airflow from the climate control system. Also, the cabin air filter is listed in the maintenance schedule on all vehicles, and periodically is scheduled for replacement in combination with other routine service items.
How much does it cost, and why?
Most cabin air filter can be replaced in less than 30 minutes by a professional automotive technician. Some filters are so easy to replace, a shop might not even have a labor charge to change the filter out during your visit.
Depending on the type and quality cabin air filter you would like to purchase, you could pay as little as $20 for a basic dust/pollen filter, to around $100 for a charcoal media filter. Some vehicles also use 2 individual filters, which doubles the price for replacement purposes.
With the relative ease and low cost of having the cabin air filter replaced, it makes sense to always change it per the manufacturers maintenance schedule. If you suffer from allergies, park under trees or bushes, or live in a high dust/pollen area, more frequent replacement of the filter is definitely suggested. Since it’s filtering the air you breathe, it’s a good idea to not skip this maintenance item.