I have a Tempstar 5000 high efficiency furnace that is about 15 years old. Recently it started reigniting off & on at the end of each cycle. Usually at about 60 second intervals. This is causing the unit to run longer and I'm afraid it might cause the ignighter to fail.
I researched it down to possibly the flame sensor but I cleaned it with steel wool and nothing changed. Next I replaced the pressure switch but no change. I also cleaned the lower A-frame and change the filters monthly. I only use the cheap see-thru filters to get max airflow.
I wanted to squeeze one more winter out of the unit since our money is tight right now. Can anyone point me in the right direction or possibly offer more suggestions?