
Furnace Blowing Cold Air
When the fan works and the fire doesn't, the house keeps losing heat while the system looks busy, so it's worth calling before the cold gets ahead of you.
When this becomes an emergency
- The vents blow steadily but the air is room temperature or cooler.
- The house has been losing ground all day despite the system running.
- There's a click and a whir at the start of each cycle but never a burner sound.
- Warm air arrives for a moment at the start and then goes cold.
What a pro does
Air without heat behind it separates the problem into halves, and the fan half is clearly fine. The work is watching the ignition sequence and finding where it breaks: no call for heat reaching the board, no spark or glow, fuel arriving but not lighting, or a flame that lights and then goes unproven a few seconds later. That last one, a flame the control can't see, is the most common version and it comes from a dirty sensing rod or a cracked ceramic on the ignitor. Propane conversions bring their own wrinkles, since orifices sized wrong for the fuel will light poorly or not at all. Forcing repeated resets past a lockout only dumps more unburned fuel into the chamber.
Frequently asked questions
Furnace Blowing Cold Air?
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