A modern furnace runs a strict startup sequence, and knowing where the sequence breaks is most of the diagnosis. The thermostat calls, the inducer motor spins up to prove draft through a pressure switch, the hot surface igniter glows, the gas valve opens, the burners light, the flame sensor confirms fire, and only then does the blower deliver heat to the house. In Tamiami, FL, the failures cluster at predictable points: an oxide-coated flame sensor, a hot surface igniter cracked from years of thermal cycling, a pressure switch that will not close because the inducer is weak or the condensate trap on a high-efficiency model has clogged, or a control board with a burned relay. Each one stops the sequence cold, and each one mimics the others from the hallway.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
Spotting the early warning signs lets you act before the problem gets expensive. Here are the most common indicators that it's time to call a professional:
- Soot, rust, or moisture near the furnace cabinet or vent pipe
- Clicking and a glowing igniter with no burner flame
- A furnace that shuts off every few minutes before the house warms up
- 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
- Booming or banging at light-off from delayed ignition
- Grinding or high-pitched squeals from the blower
Don't Wait for a Total Failure
What seems like a minor issue today can take out a compressor or heat exchanger tomorrow. Don't wait, call (645) 245-6094 and we'll take a look right away.
