Interior Filters

• The location and instructions on how to replace the cabin air filters, located inside or outside a vehicle, are not standardized. Each vehicle make and model may vary in the location, size of the filter and how to change it. Most all vehicles that place the filter inside the vehicle will locate the filter on the passenger side. Some models require removing the glove compartment assembly. In some models, this is a very simple procedure, but in others, it can be more complicated. Some GM models place the filter below the glove compartment and require removing a kick-plate panel.
  
  Once the component that conceals the access panel to the cabin air filter is removed, usually a simple slide-out door panel -- some may be retained with screws -- is removed to access the filters. The filter(s) -- some models feature dual filters -- will either sit inside a tray assembly attached to the access panel or will be stored inside the panel. Models that feature dual filters usually require removing the first one and then sliding the second one over to the first filter's position to remove.
  
  When removing the filters, pay close attention to the directional position of the filter. An arrow indicator is usually marked on the sides of the filter to identify the air flow direction. Replace the new filters with the arrow indicators in the same position.
  
  

Exterior Filters

• Exterior cabin air filters are located in the top of the firewall at the rear of the engine compartment. Some models require removing the cowl covering the windshield wipers. Others may feature separate access panels -- usually on the passenger side -- near the cowl. Exterior filters are usually a little easier to install because you don't have to remove the glove compartment assembly. Some exterior filters sit inside their own housing box, while others may feature similar access panel trays that the filter(s) sit inside. Again, pay attention to the directional air flow position of the filter.
  
  

Maintaining the Filters

• Most cabin air filters are recommended to be replaced between 12,000 and 15,000 miles. This depends on the type of driving you do and the types of area you drive your vehicle on more often. If you drive on dusty roads or in cities that experience industrial smog, you may want to change the filters more regularly. As each make and model vehicle features a variety of ways to install the filter(s) and the location of them, they may also feature different mileage intervals for replacement. Refer to the service maintenance schedule for the recommendation for your vehicle. Maintenance schedules may feature normal and severe driving conditions, which will give you the option of determining the types of driving your vehicle experiences and whether you should replace the filter more often.