It will automatically close the circuit once the sensed temperature falls approximately 30°F below the trip point

Engineered as a direct replacement for F77-5409

the sensor has likely failed or drifted out of calibration

Always check the flue pipe for debris or bird nests before resetting the manual reset switch

air from the wall cavity can skew the ambient temperature sensor readings

Nordyne 667187R Inducer Wheel It will automatically close theWhen you are dealing with a loud rattling or a failure to prove the pressure switch, it is often the Nordyne 667187R Inducer Wheel that has reached the end of its service life. This furnace inducer blower wheel is a critical OEM replacement part designed specifically for mobile home and residential gas furnaces. Measuring 3 inches by 2 inches, this wheel is compatible with a wide range of Nortek brands, including Intertherm, Miller, and Frigidaire