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 Waterbury, CT, 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
The sooner you notice these red flags, the easier and cheaper the fix. These are the signals our technicians see most often:
- Frequent on-off cycling that never reaches the thermostat setting
- Clicking and a glowing igniter with no burner flame
- Repeated shutdowns just seconds after the burners light
- A pilot or burner flame that is lazy yellow instead of crisp blue
- A fan that keeps running while the registers blow cool air
- Rust streaks, soot, or water around the cabinet or flue
- Booming or banging at light-off from delayed ignition
- Grinding or high-pitched squeals from the blower
Act Before It Gets Worse
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. If you notice any of these signs, call (203) 713-3487 for a prompt inspection.
