OEM Lennox High Limit Switch — 49K61
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The genuine OEM Lennox 49K61 high limit switch is a temperature-sensing safety control that protects your Lennox furnace from overheating. Positioned in the heat exchanger or plenum area, it continuously monitors supply air temperature and shuts off the burners if the unit exceeds its safe operating limit — typically caused by restricted airflow, a dirty filter, a failing blower, or closed registers.
Common failure symptoms: A faulty or tripped high limit switch commonly causes the furnace to short cycle — firing briefly and shutting down repeatedly — or to stop heating entirely. You may notice the blower running without heat, intermittent warm air, or a limit fault code on the control board. A switch that has drifted out of calibration can trip prematurely even when airflow is normal.
Why OEM matters: The 49K61 is calibrated to the exact trip and reset temperatures engineered for your Lennox furnace, and its terminal configuration and mounting match the factory design. Installing a non-OEM limit with different set points risks nuisance shutdowns or, worse, failure to protect the heat exchanger from heat damage. Genuine Lennox replacement ensures reliable, code-compliant overheat protection and correct system operation.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days