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 Clifton, NJ, 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.
Cooling trouble instead? See AC Repair.
Warning Signs for Furnace Repair
Spotting the early warning signs lets you act before the problem gets expensive. These are the signals our technicians see most often:
- A bang or boom when the burners ignite late
- Rust streaks, soot, or water around the cabinet or flue
- A flame that burns soft and yellow rather than steady blue
- Flames that start, last a few seconds, and go out again and again
- Clicking and a glowing igniter with no burner flame
- Grinding or high-pitched squeals from the blower
- Frequent on-off cycling that never reaches the thermostat setting
- A fan that keeps running while the registers blow cool air
Early Action Saves Money
A failing capacitor, clogged condensate drain, or dirty flame sensor rarely fixes itself and usually gets more expensive to address the longer it runs. Call (973) 200-9052 at the first sign of trouble.
