No heat on the coldest night of the year — and every HVAC company is booked and charging emergency rates. Half of no-heat calls end with a technician doing something you could have done: flipping a switch, swapping a filter, or wiping a $10 sensor. Run these checks first.
Not sure this is your exact problem?Point your camera at it — SpotFix AI diagnoses it free in seconds, with a step-by-step AR guide for your exact model.
Scan It FreeThere's a light-switch-looking toggle on or near the furnace — it gets bumped off in storage areas constantly. Check the breaker panel too.
HEAT mode, 5° above room temp. Dead thermostat batteries are an embarrassing percentage of emergency calls.
A suffocated furnace overheats and shuts itself down via the limit switch, short-cycling: fires up, runs 3 minutes, quits. New filter, problem gone.
Newer furnaces shut down when the condensate trap or line clogs. If there's a small pump or trap full of water, clear/flush it.
Turn power on, trigger heat, and watch through the sight glass. The control board's LED blinks an error code — count it and check the legend on the panel door. Scan the code and furnace label with SpotFix AI for a plain-English translation and likely part.
If the furnace ignites then dies after a few seconds, that's the classic dirty flame sensor. Power off, remove the single screw holding the thin metal rod near the burners, polish gently with fine sandpaper, reinstall. This $0 fix resolves an enormous share of no-heat calls.
50,000+ repairs diagnosed · 92% accuracy · users save $420 on average. Free on iOS.