What Is A High Limit Switch?

A lot of different parts on your furnace work together to make it run at its best. One of these things is your furnaces limit switch. The limit switch is part of your blower assembly and overall control system. If your furnaces limit switch has trouble it can prevent your furnace from operating correctly. Your limit switch does a few different things. One of the things it does is stops the fan from turning on until the air inside the furnace is warm enough. The other thing it does is kill the burner if it senses that the air around heat exchanger gets too hot in order to protect it. If your heat exchanger gets too hot it can crack and leak out harmful gasses that are supposed to be contained inside. One way to tell you have a limit switch issues is that your blower will run constantly. Your limit switch is supposed to turn off when the air cools down to a certain temperature to end the cycle of blowing warm in into your home. If your switch goes bad, it sometimes does not stop when the air reaches that cool temperature so it blows cool air instead of shutting off. If you happen to have a clogged air filter which reduces air flow your limit switch can shut off and not let the furnace run. This happens because there wont be enough air circulating around and the heat exchanger gets too hot so the limit switch senses this and shuts the burners off. This is why it is very important to get your yearly tune up to make sure the furnace is all clean and ready to go. You also have to make sure you are changing your filters each month, especially if you have a lot of dust and dander in your home. The filter will fill up fast and clog air flow into your system causing it to shut down or break. Bartlett Heating and Air can help you with all your HVAC needs so call us today!