From the hallway, a furnace that will not heat looks the same no matter what broke. Inside the cabinet, though, the sequence is strict: inducer on, pressure switch closed, igniter glowing, gas valve open, burners lit, flame proven, and finally the blower moving heat through the ducts. Most of the diagnosis comes down to finding the broken link. In Vallejo homes, it tends to be the same handful of culprits: a flame sensor coated in oxide, a hot surface igniter cracked by thermal cycling, a pressure switch held open by a tired inducer or a plugged condensate trap, or a control board with a burned relay.
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. Here are the most common indicators that it's time to call a professional:
- Loud booms at startup caused by delayed ignition
- Squeals, scrapes, or grinding noises behind the blower door
- The furnace clicks and glows but the burners never light
- Short cycling every few minutes without reaching the setpoint
- Air moving through the vents that never gets warm
- Flames that start, last a few seconds, and go out again and again
- Rust streaks, soot, or water around the cabinet or flue
- Yellow, wavering burner flames where they should be sharp blue
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. If you notice any of these signs, call (707) 210-0159 for a prompt inspection.
