For the last two or three winters my furnace would occasionally have a problem where it would fail to ignite and be left in a lockout state requiring the thermostat to be switched off then back to heat before it’d reattempt ignition. Since this was only a minor inconvenience and not repeatable I’d opted to fix it later. Suddenly this past weekend my furnace started seriously misfiring and failing to light, resulting in barely any heat on Saturday night and no heat at all on Sunday night.
Since I’ve done a bit of electronics work in the past I set about trying to troubleshoot this myself, and just after midnight this morning I was convinced that the problem was likely the main control board, Carrier part number CESO110018, as seen above in my furnace. Lacking a schematic it was difficult to troubleshoot, but I thought that it was not sending enough power to the ignition unit and thus the ignition was simply failing. So, this morning I rushed out to Behler-Young‘s Pontiac location and bought a drop-in replacement, ICM Controls‘ ICM 271 (PDF) for $68.73 (after tax). Hurring home and installing it before work I found that I was wrong; it wasn’t the control board.
I then called Mike’s Heating and Cooling, the trusted local place which replaced my air conditioner five summers ago, scheduled a time for them to come by, and set off to work leaving Danielle home in the cold where she even had to pile a robe on top of Roxie to keep her warm. The repair person arrived later in the afternoon, checked the furnace, and $285 later ($166 in parts, $79 for the service call, $40 for half an hour of labor) the ignition unit was confirmed defective, replaced, and the furnace put back into operation.
It’s a bit disappointing to have failed to repair the furnace myself, but at least it’s up and running again. Overall it’s not terribly expensive, as in the 9.5 years I’ve owned this condo I’ve likely only spent $500 on furnace maintenance, including replacing the humidifier and periodic furnace filters, but I still wish that I would have solved the problem myself.
