{"product_id":"oem-lennox-limit-switch-38m66","title":"OEM Lennox Limit Switch — 38M66","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e38M66\u003c\/strong\u003e limit switch is a high-temperature safety control that guards your Lennox furnace against overheating. Installed near the heat exchanger, it continuously senses plenum temperature and breaks the burner circuit if the furnace climbs past its safe operating limit — commonly caused by reduced airflow from a dirty filter, a failing blower motor, or obstructed ductwork.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e The furnace short-cycles on a heat call, burners fire and then shut down after a few minutes, the unit produces no heat, or the blower fails to shut off. A \u003cstrong\u003e38M66\u003c\/strong\u003e that fails open locks the furnace out of heating mode, while one that fails closed no longer protects the heat exchanger from heat-induced cracking.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e The Lennox \u003cstrong\u003e38M66\u003c\/strong\u003e is calibrated to the precise trip and reset temperatures specified for your furnace. Aftermarket switches with the wrong ratings can allow unsafe overheating or cause repeated nuisance trips. The factory-spec part guarantees accurate calibration, correct terminal and mounting fit, and the dependable protection your Lennox equipment was designed to have.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081107521907,"sku":"LNX-38M66","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-38M66.jpg?v=1783762538","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-limit-switch-38m66","provider":"National HVAC Parts","version":"1.0","type":"link"}