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 Dundalk, MD, the usual failure points are an oxide-coated flame sensor, 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.
For air conditioning breakdowns, see AC Repair.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems. These are the signals our technicians see most often:
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Water, rust stains, or black soot around the flue or cabinet
- Booming or banging at light-off from delayed ignition
- A fan that keeps running while the registers blow cool air
- Squeals, scrapes, or grinding noises behind the blower door
- Frequent on-off cycling that never reaches the thermostat setting
- Flames that start, last a few seconds, and go out again and again
- Clicking and a glowing igniter with no burner flame
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. Don't wait, call (443) 293-9736 and we'll take a look right away.
