SYMPTOM:
No heat. Exhaust blower operates. Gas valve clicks open and a rush of gas from the burners is heard but the igniter does not glow very bright or glow at all.
SOLUTION:
Check voltage going to the igniter. It should be 120V on most furnaces. If power is there and igniter is not glowing, replace the igniter. If the furnace is also equipped with a flame sensor it should be cleaned with sand cloth to prevent short cycling of the burner, reducing the life of the new igniter. A faulty igniter will usually have a crack in the element surrounded by a white powder. Average life is 4-5 years.
