Every model year of the Mercury Mariner is equipped with a cabin air filter. The purpose of the cabin air filter in the Mariner is to prevent dust and allergens from entering the car's ventilation system where it could reach the passenger cabin. Mercury recommends replacing the cabin filter every 10,000 miles, or every 12 months. If the Mariner is frequently driven on dirt roads or in heavy traffic conditions, the filter will get dirty faster. A clean cabin air filter increases air flow throughout the air conditioning system and keeps the air in the passenger area clean.
Turn off the engine. Open the hood.
Remove the screws on the cowl panel grille on the passenger side of the engine compartment. The grille is located directly below the windshield.
Lift up the cowl panel grille and set it aside.
Remove the two screws in the water shield that is now exposed.
Remove the water shield to expose the cabin air filter.
Lift out the old cabin air filter.
Insert the new cabin air filter into the filter compartment. Make sure the "air flow" indicator arrow printed on the filter is pointing down.
Replace the water shield. Install the two screws that hold the water shield in place.
