{"product_id":"oem-goodman-m4-primary-limit-switch-for-wfm18070s3axcc-20162906","title":"OEM Goodman M4 Primary Limit Switch for WFM18070S3AXCC — 20162906","description":"\u003ch2\u003eGoodman 20162906 M4 Primary Limit Switch\u003c\/h2\u003e\u003cp\u003eThe Goodman \u003cstrong\u003e20162906\u003c\/strong\u003e is a genuine OEM M4 primary limit switch (high-limit control) for the \u003cstrong\u003eWFM18070S3AXCC\u003c\/strong\u003e gas furnace. Mounted on the heat-exchanger bulkhead, this auto-reset thermal switch continuously monitors supply-air temperature and opens the control circuit to shut off the burners if the furnace overheats — typically from restricted airflow, a failed blower, or a clogged filter. Once temperatures return to normal, an auto-reset primary limit closes again and allows normal operation to resume. A failed-open or drifting switch causes short-cycling or a no-heat condition.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 20162906\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e M4 primary limit \/ high-limit switch\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFunction:\u003c\/strong\u003e Primary over-temperature safety cutout\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReset:\u003c\/strong\u003e Automatic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e Goodman WFM18070S3AXCC gas furnaces\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eOEM vs. Generic\u003c\/h3\u003e\u003cp\u003eThe M4 primary limit is calibrated to a precise trip temperature and mounting depth matched to this heat exchanger. A generic switch with a different setpoint or probe length can nuisance-trip or fail to protect the unit. For a primary combustion safety control, always fit the OEM-specced part.\u003c\/p\u003e\u003ch3\u003eInstall Difficulty\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eModerate\u003c\/strong\u003e — Remove two mounting screws and transfer the two spade connectors, roughly 15–25 minutes. Shut off gas and power first, note wire positions, and make sure the sensing element seats correctly in the airstream. If overheating persists after replacement, diagnose airflow before returning the furnace to service.\u003c\/p\u003e","brand":"Goodman","offers":[{"title":"Default Title","offer_id":63058224513395,"sku":"GOODMAN-14064","price":21.95,"currency_code":"USD","in_stock":true}],"url":"https:\/\/nationalhvacparts.com\/products\/oem-goodman-m4-primary-limit-switch-for-wfm18070s3axcc-20162906","provider":"National HVAC Parts","version":"1.0","type":"link"}