This is a BRAND NEW- White Rodgers/STEVECO/Supco Fan Relay with a 24 volt coil- Replaces Part # 90-290Q. It is used in many Furnaces and Air Conditioning systems. Thanks for looking and good luck!
Relays are switches that open and close circuits electrically. In most HVAC equipment a low voltage coil relay (24 vac) is energized in order to open or close a higher voltage (usually 120-240) circuit.