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 Stonecrest, GA, 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
The sooner you notice these red flags, the easier and cheaper the fix. Watch for these telltale signs:
- Loud booms at startup caused by delayed ignition
- Water, rust stains, or black soot around the flue or cabinet
- A furnace that shuts off every few minutes before the house warms up
- The furnace clicks and glows but the burners never light
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Squealing or grinding from the blower compartment
- Air moving through the vents that never gets warm
- Repeated shutdowns just seconds after the burners light
Act Before It Gets Worse
Most HVAC failures start small, a weak capacitor, a squealing blower, a system that runs a little longer each week. Call (470) 200-3271 at the first sign of trouble.
