What is the function of a furnace fan limit switch and how does it impact the operation of the furnace?

The function of a furnace fan limit switch is to regulate the temperature inside the furnace. It helps control when the fan turns on and off based on the temperature of the air inside the furnace. If the switch is not working properly, it can cause the fan to run continuously or not turn on at all, which can lead to overheating or inefficient heating in the furnace.