{"product_id":"oem-lennox-limit-switch-10m74","title":"OEM Lennox Limit Switch — 10M74","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e10M74\u003c\/strong\u003e limit switch is a critical safety control mounted on the heat exchanger of your Lennox furnace. It continuously monitors supply-air temperature and interrupts the gas burner circuit if the furnace overheats — typically caused by restricted airflow, a dirty filter, or a failed blower motor. This protects the heat exchanger from cracking and prevents dangerous operating conditions.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e A furnace that short-cycles (heats briefly then shuts off), no heat despite a running blower, repeated tripping on high limit, or a burner that fails to light. Over time the bimetal element can weaken, stick, or open at the wrong temperature, causing nuisance lockouts.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e The Lennox \u003cstrong\u003e10M74\u003c\/strong\u003e is calibrated to the exact trip temperature and mounting specification of your equipment. Aftermarket substitutes with different set points can trip early, run long, or fail to protect the heat exchanger. Choosing the factory part guarantees correct fit, rated calibration, and preserves your Lennox warranty coverage.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081116369267,"sku":"LNX-10M74","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-10M74.jpg?v=1783762451","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-limit-switch-10m74","provider":"National HVAC Parts","version":"1.0","type":"link"}