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 Dothan, AL, 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.
Cooling trouble instead? See AC Repair.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems. Keep an eye out for the following clues:
- Booming or banging at light-off from delayed ignition
- Clicking and a glowing igniter with no burner flame
- The blower runs constantly but the air never warms
- Grinding or high-pitched squeals from the blower
- Burners light, run a few seconds, then shut down repeatedly
- A pilot or burner flame that is lazy yellow instead of crisp blue
- A furnace that shuts off every few minutes before the house warms up
- Soot, rust, or moisture near the furnace cabinet or vent pipe
Act Before It Gets Worse
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. At the first hint of a problem, call (251) 485-1654 for a fast inspection.
