Every time your thermostat calls for heat, the furnace runs a fixed checklist. The inducer motor starts and proves draft by closing a pressure switch, the hot surface igniter heats up, the gas valve opens, the burners light, and the flame sensor confirms there is fire. Only after all of that does the blower start pushing warm air into the house. Finding the step that fails is most of the job. Around Chicago, IL, the usual failure points are a flame sensor fouled with oxide, an igniter cracked by years of heating and cooling, a pressure switch that stays open because of a weak inducer or a clogged condensate trap on a high-efficiency unit, and control boards with burned relays. Each one halts the startup, and from the hallway they all look alike.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
Spotting the early warning signs lets you act before the problem gets expensive. These are the signals our technicians see most often:
- Booming or banging at light-off from delayed ignition
- Rust streaks, soot, or water around the cabinet or flue
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Frequent on-off cycling that never reaches the thermostat setting
- The furnace clicks and glows but the burners never light
- Burners light, run a few seconds, then shut down repeatedly
- Squeals, scrapes, or grinding noises behind the blower door
- The blower runs constantly but the air never warms
Don't Wait for a Total Failure
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. Don't wait, call (872) 356-9131 and we'll take a look right away.
