Using your K&N HVAC filter is easy. First, make sure your HVAC system is turned off. Then, remove the old filter and replace it with your K&N filter, ensuring it's correctly placed according to the airflow direction indicated on the filter. As for maintenance, check the filter regularly. When it looks dirty, it's time to clean it. You can wash the filter with mild soap and water. Gently scrub the filter to remove dirt and debris, then rinse it thoroughly. Let it dry completely before reinstalling it in your HVAC system. Remember, never use harsh chemicals or abrasive materials to clean the filter as it may damage the filter media. Also, always ensure the filter is completely dry before putting it back in to prevent mold growth.