Furnace precision tune up; clean and tune up furnace; clean burners, test ignition components, adjust gas level, test safety circuit, check indoor motors, checked all electrical components, tested indoor air flow, checked heating temperatures, and tested overall furnace operation. Found the blower wheel to be dirty, this will impact airflow and cause for unhealthy air to enter throughout the home. Pulled and cleaned blower wheel to improve airflow and also provide cleaner air throughout the home. Also encouraged homeowner to upgrade to a electronic air cleaner. All other recommendations declined at this time. With age of this system. Replacement is encouraged in the future.