{"product_id":"oem-lennox-pressure-switch-assembly-78w57","title":"OEM Lennox Pressure Switch Assembly — 78W57","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e78W57\u003c\/strong\u003e pressure switch assembly is a complete venting safety control that verifies proper draft before your furnace ignites. The assembly includes the calibrated switch and its mounting hardware, sensing negative pressure from the inducer motor and closing its contacts only when adequate airflow is proven — a required step before the burners are allowed to fire.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon symptoms of a faulty pressure switch assembly:\u003c\/strong\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eInducer motor runs but the furnace fails to ignite\u003c\/li\u003e\n\u003cli\u003eFurnace short-cycles or locks out after a few minutes\u003c\/li\u003e\n\u003cli\u003ePressure switch fault codes at the control board\u003c\/li\u003e\n\u003cli\u003eIntermittent or complete loss of heat\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eAs a safety-critical component, the \u003cstrong\u003e78W57\u003c\/strong\u003e is precisely calibrated to match your Lennox furnace's inducer and flue design. Using the exact OEM assembly ensures the correct pressure setpoint, port configuration, and reliable fit — generic substitutes risk nuisance lockouts or failing to catch a real venting problem. Install the factory \u003cstrong\u003e78W57\u003c\/strong\u003e assembly to restore safe, dependable ignition on your Lennox system.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081095233907,"sku":"LNX-78W57","price":24.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-pressure-switch-single-LNX-78W57.jpg?v=1783762924","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-pressure-switch-assembly-78w57","provider":"National HVAC Parts","version":"1.0","type":"link"}