Goodman
Underfiring or Short Cycling
Furnace runs but does not keep the house warm; supply air is only slightly warm and burners cycle 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
Incorrect gas pressure setting, Oversized furnace causing short cycles, Dirty filter or coil causing limit trips, Thermostat located in poor location
How to Fix / Troubleshooting
Safety: Gas pressure and sizing issues should be handled by a licensed technician.
Steps (homeowner level):
- Replace filter: Ensure a clean filter is installed and that airflow is not restricted.
- Check vents: Open all supply and return vents to reduce static pressure and improve airflow.
- Observe run time: Note how long the furnace runs before shutting off. Very short cycles (2–5 minutes) may indicate oversizing or thermostat issues.
- Thermostat location: Ensure the thermostat is not near heat sources, drafts, or direct sunlight. Relocation may be needed.
If the furnace still fails to heat adequately, a technician should check manifold gas pressure, temperature rise, and system sizing.
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Repair Difficulty
Medium
3/5
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