The York S1-7975-3281 Fan Auto Limit Switch is a temperature-sensitive control device designed to regulate fan operation and prevent overheating in HVAC systems. It works by activating the blower fan at a set temperature and shutting down the system if excessive heat is detected. Once temperatures return to normal, it resets automatically. Commonly used in furnaces and air handlers, it ensures safe and efficient operation. Its use enhances system reliability, improves safety, and supports consistent airflow and temperature control.