Answer: Test in making notes of what you see and how the system is operating along with a combustion analysis test. Take the furnace apart clean the burners, the heat exchanger, do a visual inspection on the heat exchanger, take a look at the blower assembly making sure it's clean put back together make sure all the safeties a operational check the flame sensor and make any adjustment that is needed clock the meter making sure that the furnace is at the right firing rate