Takes about a minute. No obligation.
Furnaces in Eureka run from October through May, about eight months of the year. Overnight lows average 19°F in December, January and February, and the furnace has to make up that difference every night it drops that low. That kind of stretch adds up faster than people expect. An igniter or blower motor that would last longer somewhere milder is working through more cycles here, year after year. When something starts acting up, it's usually not out of nowhere. Getting it looked at properly means the fix holds instead of just masking the next breakdown.
NOAA nClimDiv, 1991–2020 normals
Furnaces in Eureka start running in October.
September is the month to get a weak igniter or blower motor looked at, before the first cold week finds it.
If the furnace is as old as the house, a repair might buy a few months or it might not be worth paying for. Before you pay for the fix, ask the tech how much life is left in the unit.
Find a contractor
A furnace usually gives some warning before it quits. Short cycling is one of the clearest signs. It fires up, runs a few minutes, shuts off, then starts again without ever finishing a full run. That's often a dirty flame sensor or a filter choked with dust, cutting off the airflow the furnace needs to keep going. Warm air that never feels warm enough, a faint burning smell when it first kicks on for the season, or a blower that keeps running after the burners shut off are all worth a call rather than a wait. Banging at startup is usually just the ductwork expanding as it heats. A screech from the blower motor is different. That's a bearing wearing down, and it won't quiet down on its own.
Pull the filter and hold it up to a light. If you can't see light through it, air can't get through it either, and the furnace will struggle, overheat, or shut itself off partway through a cycle. A clean filter rules out the simplest cause before anyone comes out.
Make sure the thermostat is set to heat and the temperature is actually above room temperature, not just close to it. Check that the furnace's power switch, usually a light switch on or near the unit, hasn't been bumped off. Both take a few seconds to rule out and both get missed more than people think.
Estimates for a typical Woodford County home, compared with an older unit built to the previous federal minimum, from EIA household energy data, Illinois fuel prices and NOAA climate normals. Your home will differ.
Repair makes sense when one part has failed and the heat exchanger is sound.
Replacement makes sense when the heat exchanger is cracked or the furnace keeps needing parts.
A repair is worth paying for when it fixes one part and leaves the rest of the furnace alone. A new igniter, a new flame sensor, a new capacitor, these fail on their own, and fixing one doesn't say anything about the heat exchanger or the blower motor behind it. The question changes when the repair calls for opening up the cabinet in a way that points at more trouble underneath. A cracked heat exchanger isn't something to patch and move on from, since that's the part keeping exhaust out of the air the furnace pushes into the house. If a tech has already been out for a different problem recently, that matters too. A furnace that keeps needing attention for new reasons is telling you something about its age, even if no single repair looks expensive on its own.
