The Resideo L4064B2210/B Fan & Limit Controller is a temperature-sensitive control used to manage blower operation and provide high-temperature protection in compatible heating systems. It monitors furnace or boiler temperature and activates the fan when the system reaches the selected setting, then turns it off as temperatures decrease. The limit function helps prevent overheating by... https://www.partshnc.com/resideo-l4064b2210-b-fan-and-limit-controller