Day & Night
Overheating / Limit Cycling
Furnace short cycles: burners ignite and run for 1–3 minutes, then shut off, restarting frequently.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Dirty air filter, closed or blocked supply registers, undersized ductwork, weak blower motor not moving enough air
How to Fix / Troubleshooting
Safety first: Turn off power before removing panels or filters.
- Replace filter: Locate and replace the furnace filter with a clean one of the correct size and MERV rating recommended by Day & Night.
- Open registers: Ensure at least 80% of supply registers are fully open and not blocked by furniture or rugs.
- Check blower speed: Verify that the blower runs at the correct speed for heating. A technician can adjust speed taps or ECM settings if needed.
- Monitor operation: After improving airflow, run the furnace and see if cycles lengthen to 10–15 minutes under load.
Persistent short cycling can damage the heat exchanger. Have a professional evaluate duct sizing and blower performance if the issue continues.
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Repair Difficulty
Medium
3/5
Required Part
Indoor Blower Motor
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