{"product_id":"oem-lennox-pressure-switch-33j20","title":"OEM Lennox Pressure Switch — 33J20","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e33J20\u003c\/strong\u003e pressure switch is a critical safety control that verifies proper venting and combustion airflow before your furnace's ignition sequence begins. It monitors the negative pressure created by the draft inducer motor and closes to signal the control board that it is safe to light the burners. When it fails to confirm airflow, the furnace will lock out to protect your home.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms\u003c\/strong\u003e include a furnace that ignites but shuts down shortly after, a blower that runs without heat, repeated lockouts, or diagnostic fault codes indicating a pressure switch fault. Blocked vents, a weak inducer, or a stuck or corroded switch can all trigger these issues, and a faulty \u003cstrong\u003e33J20\u003c\/strong\u003e will prevent the furnace from firing entirely.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e Lennox pressure switches are calibrated to a specific trip point matched to your furnace model's venting design. Installing the exact OEM \u003cstrong\u003e33J20\u003c\/strong\u003e ensures the switch trips at the correct pressure, preserving the safety interlock and preventing nuisance lockouts. Generic aftermarket switches with the wrong set point can cause intermittent operation or fail inspection. Choose the factory-specified part for reliable, code-compliant performance.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081109029235,"sku":"LNX-33J20","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-33J20.jpg?v=1783763024","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-pressure-switch-33j20","provider":"National HVAC Parts","version":"1.0","type":"link"}