A cabin air filter is like a filter on a home furnace or air conditioner. It removes dirt, dust and pollen from air that enters the passenger compartment through the vehicle's HVAC (heating ventilation and air conditioning) system. The filter also helps keep the A/C evaporator clean. This allows the A/C system to cool at peak efficiency and reduces the buildup of contaminants on the evaporator that contribute to the growth of microbes that can cause musty odors.
Some cabin air filters are also "combination" filters that also remove odors, diesel fumes and other pollutants. Combination filters typically have a layer of activated carbon that reacts with airborne chemicals and traps them before they can enter the cabin. The fibers in the filter media may also be electrostatically charged so they will attract and hold dirt and contaminants more efficiently.
Cabin air filters were introduced back in the mid-1980s in Audis and other European luxury vehicles. The first domestic applications date back to 1994 (Ford Contour & Mercury Mystique). Today, cabin air filters are found in almost 80% of all new vehicles.
The best way to determine if your vehicle has a cabin air filter is to look in your owner's manual. Check the index for Cabin Air Filter, or look in the section that lists scheduled maintenance items.
Use the links below to see if your vehicle has a cabin air filter, and if so, where that filter is located:
Wix Cabin Air Filter Application Guide (pdf)
Purolator Cabin Air Filter Application Help (offsite link)
Refer to your vehicle owner's manual for the exact location of the cabin air filter and how to replace it. On some applications, two filters are used in a stacked arrangement. This allows for easier filter replacement in tight quarters. Some cabin air filters are also designed to fold in the middle to make removal and installation in tight quarters easier.
Many cabin air filters are located in the HVAC plenum assembly behind the glove box. This may require removing the glove box cover to replace the filter. On some applications, this may not be necessary if there is room to pull the filter out from under or behind the glove box.
Filter replacement typically takes 10 minutes or less on the easier applications. But on others, it takes longer depending on how much disassembly is required (the glove box or console may have to be removed to reach the filter). As a rule, no special tools are needed but care must be used to make sure the filter is positioned correctly and seals tightly against its enclosure.
A simple dust only filter should last two to three years or up to 30,000 miles depending on operating conditions. More frequent filter changes may be required in dusty areas. Combination filters that also trap odors should be replaced yearly or every 15,000 miles. Refer to the vehicle owner's manual for specific service interval recommendations.