Lux
Heat Call Not Reaching Burner or Heat Strips
Thermostat calls for heat but only the fan runs and no warm air is produced
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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 wiring of W to G at furnace board, Misconfigured fan control (thermostat controlling fan instead of furnace), Open gas valve or heat strip relay
How to Fix / Troubleshooting
Safety: Turn off power and, for gas systems, close the gas shutoff valve before opening furnace panels.
- Check fan mode: Ensure the thermostat fan setting is on AUTO, not ON, when testing heat.
- Verify wiring at furnace: At the furnace control board, confirm that the W wire from the thermostat is connected to the W terminal and not mistakenly tied to G.
- Installer settings: In the Lux installer menu, set fan control to "Furnace" for gas/oil systems so the furnace controls the blower timing.
- Observe furnace: With panels in place and power restored, call for heat and watch through the sight glass. If the inducer or ignition sequence never starts, the issue is in the furnace controls and requires an HVAC technician.
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Repair Difficulty
Hard
4/5
Required Part
Furnace Control Board W Input Circuit
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