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 Royal Oak, 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.
For air conditioning breakdowns, 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
- The blower runs constantly but the air never warms
- Yellow, wavering burner flames where they should be sharp blue
- Grinding or high-pitched squeals from the blower
- A bang or boom when the burners ignite late
- Flames that start, last a few seconds, and go out again and again
- The furnace clicks and glows but the burners never light
Act Before It Gets Worse
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. Call (248) 278-4417 at the first sign of trouble.
