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 Sioux City, IA, 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
Spotting the early warning signs lets you act before the problem gets expensive. Keep an eye out for the following clues:
- The furnace clicks and glows but the burners never light
- Repeated shutdowns just seconds after the burners light
- A bang or boom when the burners ignite late
- Frequent on-off cycling that never reaches the thermostat setting
- Grinding or high-pitched squeals from the blower
- The blower runs constantly but the air never warms
- Rust streaks, soot, or water around the cabinet or flue
- Yellow, wavering burner flames where they should be sharp blue
Early Action Saves Money
What seems like a minor issue today can take out a compressor or heat exchanger tomorrow. If you notice any of these signs, call (605) 205-2271 for a prompt inspection.
