Every time your thermostat calls for heat, the furnace runs a fixed checklist. The inducer motor starts and proves draft by closing a pressure switch, the hot surface igniter heats up, the gas valve opens, the burners light, and the flame sensor confirms there is fire. Only after all of that does the blower begin sending warm air into the house. Finding the step that fails is most of the job. Around Harrisburg, PA, the usual failure points are a flame sensor fouled with oxide, an igniter cracked by years of heating and cooling, a pressure switch that stays open because of a weak inducer or a clogged condensate trap on a high-efficiency unit, and control boards with burned relays. Each one halts the startup, and from the hallway they all look alike.
When the AC quits in summer, 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:
- The igniter glows and clicks, yet no flame ever appears
- A flame that burns soft and yellow rather than steady blue
- The blower runs constantly but the air never warms
- Squealing or grinding from the blower compartment
- A bang or boom when the burners ignite late
- Repeated shutdowns just seconds after the burners light
- Water, rust stains, or black soot around the flue or cabinet
- Frequent on-off cycling that never reaches the thermostat setting
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. At the first hint of a problem, call (717) 200-9253 for a fast inspection.
