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 start pushing warm air into the house. Finding the step that fails is most of the job. Around Tustin, CA, 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.
Warning Signs for Furnace Repair
Catching these issues early helps you avoid costly problems. These are the signals our technicians see most often:
- Soot, rust, or moisture near the furnace cabinet or vent pipe
- A furnace that shuts off every few minutes before the house warms up
- Squealing or grinding from the blower compartment
- A fan that keeps running while the registers blow cool air
- Repeated shutdowns just seconds after the burners light
- Yellow, wavering burner flames where they should be sharp blue
- The igniter glows and clicks, yet no flame ever appears
- A bang or boom when the burners ignite late
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. At the first hint of a problem, call (714) 650-8573 for a fast inspection.
