Lennox
Display Power Instability
Thermostat backlight flickers or display brightness changes unexpectedly.
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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
Unstable 24V supply from Lennox indoor unit, Loose thermostat base connections, Failing display power regulator in thermostat, Electrical noise from nearby equipment
How to Fix / Troubleshooting
Safety warning: Turn off power to the indoor unit before tightening wiring.
- 1. Tighten all thermostat base terminals:
- Remove thermostat and ensure all wires are firmly clamped.
- 2. Inspect control board connections:
- Check R and C connections at the Lennox control board for looseness or corrosion.
- 3. Check for shared circuits:
- Avoid sharing the HVAC circuit with heavy loads that cause voltage dips.
- 4. Replace thermostat if flicker persists and supply is stable:
- Internal display power circuitry may be failing.
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Repair Difficulty
Medium
3/5
Required Part
Lennox Smart Thermostat
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