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The Goodman B1370198 Primary Limit Switch is the genuine OEM high-temperature safety limit for the GMNT070-3B gas furnace. Positioned over the heat exchanger, this 150°F auto-reset switch is the furnace's main overheat protection: if supply-air temperature climbs too high because of poor airflow, it shuts off the gas valve to prevent heat-exchanger damage while allowing the blower to keep cooling the cabinet.
This is a genuine Goodman OEM limit set to the precise 150°F factory value. The primary limit is the most important thermal safety in the furnace, and generic parts with drifting setpoints can cause nuisance trips or leave the heat exchanger unprotected. We strongly recommend OEM for this position.
Easy (1/5). Disconnect power, pull the two spade connectors, remove the two screws securing the switch to the heat-exchanger panel, and mount the new one. About 10 minutes with basic hand tools. Recurring trips usually point to airflow problems — replace the filter and check the blower first.
Genuine Goodman reliability with fast, dependable shipping. Confirm your model number before ordering.