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 Pontiac, MI, the failures cluster at predictable points: a flame sensor coated in oxide that can no longer prove the flame, 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
Recognizing the warning signs early can save you time and money. These are the signals our technicians see most often:
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Repeated shutdowns just seconds after the burners light
- Clicking and a glowing igniter with no burner flame
- Squealing or grinding from the blower compartment
- Rust streaks, soot, or water around the cabinet or flue
- Loud booms at startup caused by delayed ignition
- Short cycling every few minutes without reaching the setpoint
- A fan that keeps running while the registers blow cool air
Early Action Saves Money
What seems like a minor issue today can take out a compressor or heat exchanger tomorrow. Don't wait, call (248) 278-4190 and we'll take a look right away.
