{"product_id":"oem-lennox-limit-switch-18j37","title":"OEM Lennox Limit Switch — 18J37","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e18J37\u003c\/strong\u003e limit switch is a critical safety control that monitors the temperature inside your furnace's heat exchanger and plenum. When temperatures climb above the rated setpoint, this switch interrupts the burner circuit to prevent overheating, protecting both the heat exchanger and your home. It is engineered to the exact temperature threshold specified for your Lennox equipment.\u003c\/p\u003e\u003cp\u003eCommon signs of a failed \u003cstrong\u003e18J37\u003c\/strong\u003e include a furnace that short-cycles, shuts down unexpectedly mid-cycle, fails to fire, or trips repeatedly on a high-limit fault. A drifting or stuck switch can either nuisance-trip and leave you without heat or, worse, fail to open when it should.\u003c\/p\u003e\u003cp\u003eChoosing an OEM Lennox part matters because the trip temperature, mounting footprint, and electrical ratings are matched precisely to your furnace's design. A generic substitute with the wrong setpoint can cause chronic lockouts or compromise the overheat protection your system depends on. Installing the exact factory \u003cstrong\u003e18J37\u003c\/strong\u003e restores reliable, safe operation and preserves your equipment warranty.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081114108275,"sku":"LNX-18J37","price":19.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-limit-switch-snap-disc-LNX-18J37.jpg?v=1783762466","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-limit-switch-18j37","provider":"National HVAC Parts","version":"1.0","type":"link"}