Lennox
Short Cycling Due to Control or Sizing Issues
Furnace cycles on and off frequently, causing temperature swings and high energy use.
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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
Oversized Lennox furnace for home, Thermostat located near heat source, Dirty flame sensor causing intermittent flame loss, Improper staging configuration
How to Fix / Troubleshooting
Safety: Turn off power before accessing furnace internals.
- 1. Thermostat location: Ensure thermostat is not near supply registers, sunlight, or appliances.
- 2. Clean flame sensor: As described earlier, clean the flame sensor to prevent nuisance dropouts.
- 3. Check staging settings: Verify thermostat and furnace staging are configured correctly.
Oversizing issues require a professional load calculation and may not be fully correctable without equipment changes.
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Repair Difficulty
Medium
3/5
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