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 Birmingham, AL, 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.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems. Here are the most common indicators that it's time to call a professional:
- Booming or banging at light-off from delayed ignition
- A flame that burns soft and yellow rather than steady blue
- Water, rust stains, or black soot around the flue or cabinet
- Flames that start, last a few seconds, and go out again and again
- A furnace that shuts off every few minutes before the house warms up
- Air moving through the vents that never gets warm
- Squeals, scrapes, or grinding noises behind the blower door
- The furnace clicks and glows but the burners never light
Act Before It Gets Worse
A failing capacitor, clogged condensate drain, or dirty flame sensor rarely fixes itself and usually gets more expensive to address the longer it runs. Call (659) 276-7527 at the first sign of trouble.
