The Subaru Legacy cabin air filter is similar to your engine air filter, but its filtering capability is much greater. It cleans ambient air from any pollen and dirt so that you can breathe clean and fresh air. Where you live will be the single greatest contributor to how often you must change the cabin air filter in your Subaru. If you live in an area that has a lot of construction, you may need to change the filter very often. As a general guideline, however, replace your cabin air filter every 20,000 miles.
Open the glove compartment.
Remove the cable holding the glove compartment door with your hand, and squeeze the glove box together where it holds onto the dashboard. Then swing the door down toward the floor.
Remove the cabin air filter cover by pinching the clips at both ends with your fingers and pulling back.
Remove the cabin air filter, and inspect it for dirt and dust. If it is very dirty, go ahead and replace it. If it has only a light dusting, you can reuse it.
Install the new cabin air filter in the old one's place.
Reattach the cable to the glove box door, and close the glove box.
