Every time your thermostat calls for heat, the furnace works through 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 start pushing warm air into the house. Finding the step that fails is most of the job. Around Bethlehem, 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.
Cooling trouble instead? 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:
- Rust streaks, soot, or water around the cabinet or flue
- Flames that start, last a few seconds, and go out again and again
- Frequent on-off cycling that never reaches the thermostat setting
- Loud booms at startup caused by delayed ignition
- Squeals, scrapes, or grinding noises behind the blower door
- The igniter glows and clicks, yet no flame ever appears
- The blower runs constantly but the air never warms
- A flame that burns soft and yellow rather than steady blue
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. Call (610) 788-0052 at the first sign of trouble.
