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 Greensboro, NC, 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.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
Spotting the early warning signs lets you act before the problem gets expensive. Keep an eye out for the following clues:
- A flame that burns soft and yellow rather than steady blue
- The furnace clicks and glows but the burners never light
- Burners light, run a few seconds, then shut down repeatedly
- Loud booms at startup caused by delayed ignition
- Short cycling every few minutes without reaching the setpoint
- Grinding or high-pitched squeals from the blower
- The blower runs constantly but the air never warms
- Soot, rust, or moisture near the furnace cabinet or vent pipe
Early Action Saves Money
A failing capacitor, clogged condensate drain, or dirty flame sensor rarely fixes itself and usually gets more expensive to address the longer it runs. Don't wait, call (743) 202-6572 and we'll take a look right away.
