SYMPTOM:
After removing the clogged air filter the furnace starts up normally and after a few seconds running the blower comes on and then the burner goes out. After another few seconds the burner comes back on and the same thing happens all over.
SOLUTION:
Remove the leads from the high limit and bypass the switch by putting a jumper between the wires you removed. Test run furnace and see if it runs continuously. If it does check temperature rise and see if it is within the specified range as listed on the nameplate. If it is and the problem is still occurs the limit should be replaced. When a filter is very dirty the temperature in the furnace rises and causes the high limit to open and close frequently. This puts the limit switch out of calibration and a 165F limit switch could open at 100F.
