{"product_id":"oem-lennox-pressure-switch-33j90","title":"OEM Lennox Pressure Switch — 33J90","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e33J90\u003c\/strong\u003e pressure switch is a critical safety control that confirms proper venting and combustion-air draft before your Lennox furnace is allowed to ignite. It senses the negative pressure created by the inducer motor and closes its contacts only when airflow is adequate, preventing the furnace from firing under unsafe conditions that could allow flue gases to spill.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms:\u003c\/strong\u003e A failing \u003cstrong\u003e33J90\u003c\/strong\u003e or a draft problem it detects often shows up as a furnace that will not light, ignition that starts then quickly shuts down, a blower that runs without heat, or a control board flashing a pressure-switch or lockout fault code. A stuck-open switch, cracked hose, or blocked vent will keep the sequence from advancing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e Pressure switches are calibrated to a specific trip point (in inches of water column) matched to your furnace's venting design. The factory Lennox \u003cstrong\u003e33J90\u003c\/strong\u003e carries the exact set point and electrical rating your unit requires, so it protects against dangerous venting faults and passes the ignition sequence correctly — reliability a generic switch with the wrong calibration cannot guarantee.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081108799859,"sku":"LNX-33J90","price":24.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0984\/1190\/5395\/files\/nhvac-draft-inducer-LNX-33J90.jpg?v=1783763028","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-pressure-switch-33j90","provider":"National HVAC Parts","version":"1.0","type":"link"}