Replacement is necessary if the fan guard shows signs of heavy oxidation

As a Lochinvar fan motor replacement

This unit features a totally enclosed design to ensure quiet operation and protection against environmental contaminants

and BG coils for flexible electrical integration

it serves as the central processing unit

Williams P323080 Fan Switch 321702-401 Replacement is necessary if theThe Williams P323080 Fan Switch is a critical OEM replacement part engineered for precise thermal control in Williams Monterey furnaces and direct vent gas heaters. This furnace fan limit switch functions as a normally open, temperature actuated control, ensuring the blower motor engages only when the heat exchanger reaches the appropriate operating temperature. This prevents the circulation of cold air during the heat up cycle and protects the system