The Marley Engineered Products 410101001 is a 24V fan auto-relay designed for use in HVAC systems. Based on predetermined parameters or signals from the system's controllers, this relay automatically regulates the fan's operation. In order to maintain the appropriate temperature or airflow within the HVAC equipment, it receives input signals from the thermostat and then turns on or of... https://www.partshnc.com/410101001-marley-engineered-products-24v-fan-auto-relay