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 begin sending warm air into the house. Finding the step that fails is most of the job. Around Baltimore, MD, 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. Any one of them halts the startup, and from the hallway they all look alike.
For air conditioning breakdowns, see AC Repair.
Warning Signs for Furnace Repair
Recognizing the warning signs early can save you time and money. Watch for these telltale signs:
- Rust streaks, soot, or water around the cabinet or flue
- Booming or banging at light-off from delayed ignition
- Flames that start, last a few seconds, and go out again and again
- Air moving through the vents that never gets warm
- Clicking and a glowing igniter with no burner flame
- Yellow, wavering burner flames where they should be sharp blue
- Squeals, scrapes, or grinding noises behind the blower door
- A furnace that shuts off every few minutes before the house warms up
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 (443) 293-9678 at the first sign of trouble.
