A modern furnace runs a strict startup sequence, and knowing where the sequence breaks is most of the diagnosis. The thermostat calls, the inducer motor spins up to prove draft through a pressure switch, the hot surface igniter glows, the gas valve opens, the burners light, the flame sensor confirms fire, and only then does the blower deliver heat to the house. In Columbia, MO, the failures cluster at predictable points: an oxide-coated flame sensor, a hot surface igniter cracked from years of thermal cycling, a pressure switch that will not close because the inducer is weak or the condensate trap on a high-efficiency model has clogged, or a control board with a burned relay. Each one stops the sequence cold, and each one mimics the others from the hallway.
For air conditioning breakdowns, 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:
- Clicking and a glowing igniter with no burner flame
- Rust streaks, soot, or water around the cabinet or flue
- Booming or banging at light-off from delayed ignition
- Short cycling every few minutes without reaching the setpoint
- Repeated shutdowns just seconds after the burners light
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Air moving through the vents that never gets warm
- Squeals, scrapes, or grinding noises behind the blower door
Don't Wait for a Total Failure
What seems like a minor issue today can take out a compressor or heat exchanger tomorrow. Don't wait, call (573) 203-0636 and we'll take a look right away.
