LENNOX ELITE FURNACE SHORT CYCLING General Troubleshooting
| CONF | DIAGNOSIS | ACTION |
|---|---|---|
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96%
CONF
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High-Efficiency Furnace Air Filter (MERV 11)
The most frequent cause of short cycling is restricted airflow due to a loaded filter. This causes the internal cabinet temperature to rise rapidly, triggering the high-limit safety switch to break the 24V circuit to the gas valve. Replacing the filter restores proper CFM across the heat exchanger, keeping temperatures below the trip threshold.
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|
|
2%
CONF
|
Flame Sensor
Lennox units often experience carbon or silica buildup on the flame sensor rod, which prevents the 'flame rectification' process. If the control board does not detect a steady microamp signal within seconds of ignition, it will shut off the gas valve for safety. A new sensor ensures the control board accurately detects the burner flame.
SKU: 71W80
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|
|
2%
CONF
|
Primary High Limit Switch
If airflow is confirmed to be adequate but the unit continues to cycle, the high-limit switch may have become 'weak' due to repeated thermal cycling or mechanical fatigue. This bimetallic disc switch is designed to fail open for safety; if it trips prematurely or fails to reset properly, the furnace will cycle regardless of actual heat exchanger temperature.
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DIY Repair Guide
Watch exactly how to replace the High-Efficiency Furnace Air Filter (MERV 11).
// NOTICE:
This report is generated by an Agentic AI Engineer utilizing probabilistic modeling.
PartSniper is an automated parts recommender service. AI-generated results may not be correct. This data is not a substitute for professional engineering advice or manual inspection. Always verify part compatibility and disconnect power before any repair. PartSniper is not liable for inaccuracies, injury, or damage.