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 New Orleans, LA, the failures cluster at predictable points: a flame sensor coated in oxide that can no longer prove the flame, 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:
- Water, rust stains, or black soot around the flue or cabinet
- A pilot or burner flame that is lazy yellow instead of crisp blue
- The furnace clicks and glows but the burners never light
- Burners light, run a few seconds, then shut down repeatedly
- Air moving through the vents that never gets warm
- A furnace that shuts off every few minutes before the house warms up
- Squeals, scrapes, or grinding noises behind the blower door
- Loud booms at startup caused by delayed ignition
Don't Wait for a Total Failure
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 (504) 531-6048 for a prompt inspection.
