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 Edina, MN, 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
Spotting the early warning signs lets you act before the problem gets expensive. Keep an eye out for the following clues:
- A bang or boom when the burners ignite late
- Grinding or high-pitched squeals from the blower
- A furnace that shuts off every few minutes before the house warms up
- The igniter glows and clicks, yet no flame ever appears
- Air moving through the vents that never gets warm
- A flame that burns soft and yellow rather than steady blue
- Flames that start, last a few seconds, and go out again and again
- Soot, rust, or moisture near the furnace cabinet or vent pipe
Act Before It Gets Worse
Most HVAC failures start small, a weak capacitor, a squealing blower, a system that runs a little longer each week. If you notice any of these signs, call (952) 295-1557 for a prompt inspection.
