Furnace short cycling
Starts, runs briefly, shuts off, repeats. Ranked from 1,600 repairs on furnaces with this symptom — and the first thing to rule out costs nothing.
Before you start — Kill the power before you touch anything gas · electrical safety
Switch the furnace off at the service switch AND at the breaker before opening the cabinet. A furnace that short cycles on a limit switch is telling you it is overheating — find out why rather than replacing the limit that is protecting it. Heat-exchanger inspection is licensed-tech work.
If you smell gas, or if the furnace short cycles with a burnt or acrid smell: stop, leave the building and call your gas utility from outside.
Narrow it down
My furnace runs for a few minutes then shuts off — what's wrong?
A furnace that runs several minutes and then quits is usually overheating and tripping its limit switch — and the cause is almost always airflow. Change the filter and open the supply registers first; that is a $10 fix and it resolves most of these. If it still trips, the limit switch itself (43%) or a failing blower motor (24%) is next.
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Also check — 43%43% of matching repairs
Running for minutes and then stopping is the limit doing its job. Replace it only after you have ruled out the airflow that made it trip.
Try this first: Change the filter and open every register first — that alone fixes most limit-trip cycling.
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Also check — 24%
BLM-1075
3/4 HP Multi-Speed Blower Motor
Low stock — 4 left · ships today
$184.00 Pro price $156.40 save $27.60 (15%)24% of matching repairsA blower running slow or dropping out on thermal overload starves the heat exchanger of air and trips the limit.
The remaining 33% of matching repairs resolved without a replacement part — a filter, a reset or a thermostat setting.
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