First, the exception: if you smell gas, don't troubleshoot. Leave the house and call your gas utility's emergency line from outside, then call us. Everything below assumes no gas smell.
A meaningful share of 'dead furnace' calls end at the thermostat: dead batteries, a schedule that flipped to away mode, or a setting nudged to cool. Check it first — set it to heat, 3–4 degrees above room temperature.
Next: the furnace switch (it looks like a light switch, near the unit — someone flips it off surprisingly often), the breaker panel, and the filter. A filter choked with dust can trip the furnace's safety limit and shut heat down completely.
Finally, check the exterior intake and exhaust pipes for snow or ice blockage after a storm, and confirm the furnace door is fully seated — many models refuse to run with the panel ajar. Still nothing? Now it's our problem: call us and we'll troubleshoot live before dispatching.
The 6 checks
- Thermostat: heat mode, batteries, setpoint up
- Furnace power switch is on
- Breaker hasn't tripped
- Filter isn't clogged
- Intake/exhaust pipes clear of snow and ice
- Furnace door panel fully closed
Related
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