Concord
Burners Not Igniting or Short Cycling
Furnace runs but does not produce warm air; blower is on, air from registers is cool or only slightly warm.
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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
Faulty hot surface ignitor, Closed manual gas shutoff valve, Faulty gas valve, Faulty integrated furnace control board
How to Fix / Troubleshooting
Safety: Turn off power and gas before removing burner access panels. If you smell gas, do not attempt to light the furnace; evacuate and call the gas utility.
Steps:
- Check thermostat mode: Ensure thermostat is set to HEAT, not FAN ONLY or COOL.
- Verify gas supply: Confirm the gas cock near the Concord furnace is parallel to the pipe (open). Check that other gas appliances work.
- Observe ignition: With panels in place and power on, call for heat and watch through the sight glass. See if the ignitor glows and if burners light. If the ignitor never glows, test and replace it as needed. If it glows but burners do not light, suspect the gas valve or gas pressure.
- Listen for short cycling: If burners light briefly then shut off, check for limit or flame sense issues as indicated by LED codes.
Note: Gas valve replacement and gas pressure adjustments must be done by a licensed technician.
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Repair Difficulty
Hard
4/5
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