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 airflow, checked heating temperatures, and tested overall furnace function. Upon inspection found that the main flame safety sensor had failed, if this doesn't get replaced the furnace will fail to run. Also found the furnace blower wheel was extremely dirty, this will cause the furnace to not run as efficient. Also found the inducer draft motor was testing higher then the rated plate. This will continue to cause damage to that motor. Lastly found the motor starter for the blower motor to be testing range, once this is out it will start to cause damage to the motor. With the age and condition of this system replacement would be highly encouraged.