Came out to call for a system not heating properly. Customer stated that the unit was just blowing cool air, but no heat. I checked the system over an found the unit to be locked out and the blower running. Shut system off, and cycled it back on from the control board. Furnace started heating sequence but the hot surface ignitor wasn’t glowing. I had correct power to it, but the ignitor itself had a short in it. Showed customer and explained what needed to be repaired. Customer approved repair to get system running. Furnace and coil are 23 years old and in fair condition. Recommend customer plan for replacement of system due to age, condition and cost of repairs that can start to add up.