Description
The Trane CNT03780 SPST Automatic Reset Limit Control Switch is a normally closed temperature-sensing part used in HVAC systems to monitor and regulate plenum air temperature. It operates at approximately 155F and opens its circuit when this temperature is exceeded, interrupting power to the heating element until the condition resets automatically once the unit cools. This limit switch is mounted inside the furnace supply plenum where it protects the heat exchanger and other components from overheating during normal operation or airflow faults. Within the furnace or air-handler control sequence it act as a safety interlock that contributes to safe cycling.
