{"product_id":"oem-lennox-pressure-switch-36w49","title":"OEM Lennox Pressure Switch — 36W49","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e36W49\u003c\/strong\u003e pressure switch is a safety control that confirms proper draft and airflow before your Lennox furnace is allowed to ignite. As the inducer motor starts, it creates negative pressure sensed through the switch's port; the \u003cstrong\u003e36W49\u003c\/strong\u003e must close to prove that combustion gases will vent safely and that the flue is not blocked. Only after this proving signal reaches the control board will the ignition sequence continue — making the switch a critical link in safe furnace operation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e a faulty or tripped pressure switch typically stops ignition and triggers a lockout, often shown as a specific flash code. Symptoms include a furnace that runs the inducer but never lights, short cycling, and no heat. Note that a stuck-open switch can also be signaling a real problem — a blocked flue, cracked hose, condensate-clogged port, or failing inducer — so verify airflow before replacing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e pressure switches are calibrated to a precise trip point in inches of water column specific to your Lennox model. An aftermarket switch with the wrong setpoint may fail to prove or, worse, prove when it shouldn't — defeating a safety function. The factory \u003cstrong\u003e36W49\u003c\/strong\u003e guarantees the correct calibration and fit for safe, code-compliant operation.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081088745843,"sku":"LNX-36W49","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-36W49.jpg?v=1783763034","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-pressure-switch-36w49","provider":"National HVAC Parts","version":"1.0","type":"link"}