OEM Lennox Furnace Limit Switch — 19M00
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The genuine OEM Lennox 19M00 limit switch is a critical safety control in your Lennox gas furnace. Mounted on the heat exchanger or plenum, it continuously monitors supply-air temperature and cuts power to the gas valve if the furnace overheats — protecting the heat exchanger, wiring, and your home from dangerous high-temperature conditions. It is built to the exact temperature calibration Lennox specifies for the 19M00 application.
A failing limit switch produces telltale symptoms: the furnace short-cycles, shuts off before reaching the set temperature, trips repeatedly on high limit, or fails to fire because the switch is stuck open. A limit that stays closed when it should open is a serious safety concern, allowing the furnace to run past safe temperatures.
OEM matters here more than almost anywhere else. The 19M00 is calibrated to trip at a precise temperature threshold matched to your furnace's design. A substitute switch with the wrong rating can either nuisance-trip or, worse, fail to protect the equipment. Installing the factory part restores proper overheat protection and reliable heating.
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