Furnace runs but delivers insufficient heat; home never reaches set temperature.
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.
Possible Causes
How to Fix / Troubleshooting
Safety: Gas pressure and orifice sizing must be checked by a licensed technician. Do not adjust gas valve yourself.
- Replace air filter: Ensure proper airflow so heat is distributed effectively.
- Check supply registers: Confirm all registers are open and not blocked.
- Inspect burners: With power and gas off, remove and clean burners to ensure full flame across each burner.
- Verify thermostat location: Make sure thermostat is not in a drafty area or near heat sources that can misread room temperature.
If the furnace still underheats, a technician should measure temperature rise and gas input to confirm proper firing rate.
Repair Difficulty
Required Part
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