OEM Lennox High Limit Switch — 26H66
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The genuine OEM Lennox 26H66 high limit switch is a temperature-sensing safety control that guards your furnace against overheating. Mounted near the heat exchanger, it monitors plenum temperature and shuts off the gas valve if the furnace runs too hot — protecting the heat exchanger, blower components, and your home from heat-related damage.
Common failure symptoms: When the 26H66 fails or trips, the furnace often produces no heat, short-cycles on and off, or shuts down after a few minutes of operation. Overheating from a dirty filter, blocked ductwork, or a failing blower motor can repeatedly trip the limit, and a switch that has opened permanently will keep the burners locked out until it is replaced.
Why OEM matters: The 26H66 is calibrated to the exact open and close temperatures and the mounting configuration Lennox specifies for your furnace. A generic limit with the wrong trip point may allow dangerous overheating or cause constant nuisance shutdowns. Installing the factory OEM switch restores accurate overheat protection and the safe, reliable operation your Lennox furnace was designed to deliver.
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