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 begin sending warm air into the house. Finding the step that fails is most of the job. Around Coeur d'Alene, ID, 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. These are the signals our technicians see most often:
- A furnace that shuts off every few minutes before the house warms up
- Water, rust stains, or black soot around the flue or cabinet
- Grinding or high-pitched squeals from the blower
- Flames that start, last a few seconds, and go out again and again
- Air moving through the vents that never gets warm
- The furnace clicks and glows but the burners never light
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Loud booms at startup caused by delayed ignition
Early Action Saves Money
Most HVAC failures start small, a weak capacitor, a squealing blower, a system that runs a little longer each week. If you notice any of these signs, call (208) 208-1842 for a prompt inspection.
