{"product_id":"lennox-73w18-genuine-oem-auto-reset-limit-switch-120-150-f","title":"Lennox 73W18 – Genuine OEM Auto Reset Limit Switch (120-150°F)","description":"\u003ch1 class=\"MsoNormal\"\u003eLennox 73W18 – Genuine OEM Auto Reset Limit Switch (120-150°F)\u003c\/h1\u003e\n\u003cp class=\"MsoNormal\"\u003eThe \u003cb\u003eLennox 73W18\u003c\/b\u003e is a genuine OEM primary auto-reset limit switch designed for \u003cb\u003eLennox and Allied Air\u003c\/b\u003e furnaces. This critical safety component monitors the heat exchanger’s temperature to ensure the system operates within safe thermal parameters. If the furnace overheats due to restricted airflow or mechanical failure, this switch \"opens\" to shut down the burners, preventing equipment damage and potential fire hazards.\u003c\/p\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\u003cb\u003eTechnical Performance\u003c\/b\u003e\u003c\/h2\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cbr\u003eThis high-precision limit switch features a specific temperature range of \u003cb\u003e120°F to 150°F\u003c\/b\u003e, easily identified by its distinct \u003cb\u003epurple protective sleeve\u003c\/b\u003e. As an \"Auto Reset\" part, it is designed to close the circuit automatically once temperatures return to a safe level. Being a \"Genuine OEM\" part ensures the internal bimetal disc is calibrated to Lennox’s exact safety specifications, providing a more reliable response time and longer cycle life than generic alternatives.\u003c\/p\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\u003cb\u003eKey Features and Function:\u003c\/b\u003e\u003c\/h2\u003e\n\u003cul style=\"margin-top: 0in;\" type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l2 level1 lfo1; tab-stops: list .5in;\"\u003e\n\u003cb\u003eThermal Safety Integration:\u003c\/b\u003e Prevents furnace overheating by breaking the electrical circuit to the gas valve when the 150°F threshold is reached.\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l2 level1 lfo1; tab-stops: list .5in;\"\u003e\n\u003cb\u003eAuto-Reset Logic:\u003c\/b\u003e Automatically restores furnace operation once the heat exchanger cools to 120°F, reducing unnecessary \"locked out\" service calls.\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l2 level1 lfo1; tab-stops: list .5in;\"\u003e\n\u003cb\u003ePurple Sleeve Identification:\u003c\/b\u003e Color-coded for easy field identification, ensuring the correct temperature-rated part is installed during repair.\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l2 level1 lfo1; tab-stops: list .5in;\"\u003e\n\u003cb\u003eDirect-Fit Design:\u003c\/b\u003e Features standard 1\/4\" male spade terminals and a flat-mount flange for quick, plug-and-play replacement.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\u003cb\u003eProduct Details and Key Specifications:\u003c\/b\u003e\u003c\/h2\u003e\n\u003cul style=\"margin-top: 0in;\" type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003ePart Number:\u003c\/b\u003e 73W18\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003eManufacturer:\u003c\/b\u003e Lennox \/ Allied Air (Genuine OEM)\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003ePart Type:\u003c\/b\u003e Primary Auto-Limit Switch (L150-30)\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003eOpen Temperature:\u003c\/b\u003e 150°F (30°F Differential)\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003eClose Temperature:\u003c\/b\u003e 120°F\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003eColor Code:\u003c\/b\u003e Purple Sleeve\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l1 level1 lfo2; tab-stops: list .5in;\"\u003e\n\u003cb\u003eShipping Weight:\u003c\/b\u003e 0.2 lbs\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\n\u003cspan style=\"font-family: 'Segoe UI Emoji',sans-serif; mso-bidi-font-family: 'Segoe UI Emoji';\"\u003e🛠️\u003c\/span\u003e \u003cb\u003eHVAC Depot Pro Tip: Check Your Airflow\u003c\/b\u003e\n\u003c\/h2\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cbr\u003eIf you find this limit switch has tripped, investigate the cause rather than just swapping the part. A \"limit trip\" is almost always a symptom of an \u003cb\u003eairflow issue\u003c\/b\u003e. Before finishing the job, check for a dirty air filter, blocked return grilles, or a failing blower motor capacitor. Installing a new switch without fixing the airflow will likely lead to a repeat failure within hours.\u003c\/p\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\u003cb\u003eCross-Reference \u0026amp; Compatibility:\u003c\/b\u003e\u003c\/h2\u003e\n\u003cp class=\"MsoNormal\"\u003e\u003cbr\u003eThe 73W18 is a direct OEM replacement for the following part numbers:\u003c\/p\u003e\n\u003cul style=\"margin-top: 0in;\" type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l3 level1 lfo3; tab-stops: list .5in;\"\u003e\n\u003cb\u003eOEM Numbers:\u003c\/b\u003e 73W1801, 100445-12, 36T01B3-30006, 49L59, 49L5901\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l3 level1 lfo3; tab-stops: list .5in;\"\u003e\n\u003cb\u003eAlternative Brands:\u003c\/b\u003e Fits Armstrong, Ducane, and Concord (Allied Air brands)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 class=\"MsoNormal\"\u003e\u003cb\u003eExtensive Model Compatibility List:\u003c\/b\u003e\u003c\/h2\u003e\n\u003cul style=\"margin-top: 0in;\" type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l0 level1 lfo4; tab-stops: list .5in;\"\u003e\n\u003cb\u003eLennox Series:\u003c\/b\u003e Used extensively in \u003cb\u003eG40, G41, G50, G51, G60, and G61\u003c\/b\u003e gas furnace series.\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-list: l0 level1 lfo4; tab-stops: list .5in;\"\u003e\n\u003cb\u003eAllied Air Series:\u003c\/b\u003e Fits various \u003cb\u003e90UGF and 80UHG\u003c\/b\u003e furnace models.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Lennox","offers":[{"title":"Default Title","offer_id":53069695484267,"sku":"66255141842","price":72.79,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0922\/9683\/9531\/files\/73W18.jpg?v=1775519067","url":"https:\/\/tophvacparts.com\/products\/lennox-73w18-genuine-oem-auto-reset-limit-switch-120-150-f","provider":"HVAC Parts and Equipment Depot","version":"1.0","type":"link"}