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 sending heat through the house. Diagnosis is mostly a matter of finding where that chain breaks. In Castle Rock 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.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
The sooner you notice these red flags, the easier and cheaper the fix. Keep an eye out for the following clues:
- A pilot or burner flame that is lazy yellow instead of crisp blue
- Clicking and a glowing igniter with no burner flame
- Flames that start, last a few seconds, and go out again and again
- Water, rust stains, or black soot around the flue or cabinet
- Grinding or high-pitched squeals from the blower
- Loud booms at startup caused by delayed ignition
- Frequent on-off cycling that never reaches the thermostat setting
- The blower runs constantly but the air never warms
Early Action Saves Money
What seems like a minor issue today can take out a compressor or heat exchanger tomorrow. Don't wait, call (970) 602-4978 and we'll take a look right away.
