{"product_id":"oem-lennox-limit-switch-29m75","title":"OEM Lennox Limit Switch — 29M75","description":"\u003cp\u003eThe genuine OEM Lennox \u003cstrong\u003e29M75\u003c\/strong\u003e limit switch is a temperature-sensing safety control that monitors heat inside your Lennox furnace. If the plenum temperature climbs above a safe threshold — typically due to restricted airflow — the switch opens to shut off the burners, preventing overheating and protecting the heat exchanger from damage. It's a small but critical safety device in the furnace's control sequence.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCommon failure symptoms\u003c\/strong\u003e include a furnace that short cycles (burners igniting then quickly shutting off), no heat, the blower running continuously, or repeated safety lockouts. A limit switch can fail open (blocking ignition entirely) or fail closed (defeating its protective function), so accurate testing is important before replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy OEM matters:\u003c\/strong\u003e the Lennox \u003cstrong\u003e29M75\u003c\/strong\u003e is set to the precise temperature trip point and physical dimensions your furnace model requires. A mismatched aftermarket switch may trip too early, too late, or not at all — compromising both comfort and safety. Installing the correct OEM limit switch restores proper protection and reliable heating. Always disconnect power before servicing, and address any underlying airflow restriction, such as a dirty filter or blocked ducts, that may have caused the switch to trip.\u003c\/p\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":63081109619059,"sku":"LNX-29M75","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-29M75.jpg?v=1783762504","url":"https:\/\/nationalhvacparts.com\/products\/oem-lennox-limit-switch-29m75","provider":"National HVAC Parts","version":"1.0","type":"link"}