The cabin air filter in an Audi A3 keeps allergens, dust and debris out of the vehicle's air conditioning system. A dirty cabin air filter will cause the motors in the air conditioning system to have to work harder. Replacing a dirty cabin air filter in an A3 with a clean filter will increase air flow in the passenger cabin. Audi recommends replacing the cabin air filter in the A3 once a year or every 10,000 miles. Driving in dusty conditions will cause the cabin filter to become dirty more quickly. Whenever a cabin air filter becomes dirty or clogged, it should be replaced.
Open the hood. Locate the cowl on the passenger side where the cabin air filter cover is.
Remove the screw from the cowl cover with the Philips-head screwdriver. Push the cover toward the front of the vehicle to remove it.
Push up on the filter to loosen it from the filter housing. Pull the filter toward the front of the vehicle to remove it from the housing.
Insert the new filter by lining up the notches on the sides of the filter frame to the grooves in the filter housing.
Replace the cowl cover. Replace the screw that holds the cover in place.