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 St. Augustine, FL, 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.
When to Call for Furnace Repair in St. Augustine
The sooner you notice these red flags, the easier and cheaper the fix. Watch for these telltale signs:
- Short cycling every few minutes without reaching the setpoint
- The furnace clicks and glows but the burners never light
- Squeals, scrapes, or grinding noises behind the blower door
- A fan that keeps running while the registers blow cool air
- Yellow, wavering burner flames where they should be sharp blue
- Burners light, run a few seconds, then shut down repeatedly
- Water, rust stains, or black soot around the flue or cabinet
- Loud booms at startup caused by delayed ignition
Don't Wait for a Total Failure
A failing capacitor, clogged condensate drain, or dirty flame sensor rarely fixes itself and usually gets more expensive to address the longer it runs. At the first hint of a problem, call (904) 243-4271 for a fast inspection.
