Every time your thermostat calls for heat, the furnace works through 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 begin sending warm air into the house. Finding the step that fails is most of the job. Around Berwyn, 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. Any one of them 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
The sooner you notice these red flags, the easier and cheaper the fix. Watch for these telltale signs:
- Clicking and a glowing igniter with no burner flame
- Frequent on-off cycling that never reaches the thermostat setting
- Air moving through the vents that never gets warm
- A flame that burns soft and yellow rather than steady blue
- Flames that start, last a few seconds, and go out again and again
- Grinding or high-pitched squeals from the blower
- Soot, rust, or moisture near the furnace cabinet or vent pipe
- A bang or boom when the burners ignite late
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. Call (708) 536-4738 at the first sign of trouble.
