Using and Maintaining HVAC Systems in Rental Properties

2 Signs The Limit Switch In Your Home's Furnace Is Going Bad

While the thermostat in your house helps to regulate the temperature by sending signals to the furnace to kick on, the limit switch serves the same purpose inside the system. It detects when the internal temperature becomes too cold or hot so that the furnace and blower fan will turn off.

When the limit switch goes bad, your furnace will not be able to function properly. Below are a couple of the signs you should be on the lookout for when trying to determine whether the limit switch is bad and needs to be repaired by a professional.

1. Blower Fan Continues to Run Long after the Furnace Itself Kicks Off 

One sign that your furnace's limit switch has started to go bad is when you notice that the blower fan seems to run constantly. Even after the furnace itself has kicked off, the fan will continue to run, blowing cold air throughout your house.

While it is normal for the blower to run after the furnace turns off, it should only run until the internal temperature of the system has cooled down. However, since the limit switch is malfunctioning, it will not send the signal to turn the blower off until long after the fan is needed. 

2. Furnace Turns off Almost as Soon as It Kicks On, Causing the System to Short Cycle 

Another sign that the limit switch inside your home's heating system is failing is when the furnace starts to short cycle. Within a couple of minutes of the furnace coming on, it will shut itself off without the blower fan even having a chance to kick on.

If the limit switch has become overly sensitive to heat, it will send the signal to the furnace to shut off after just a little rise in the temperature. Because the furnace never gets hot enough for the blower to come on, your home will stay cool.

When the limit switch in your home's furnace goes bad, the system will no longer be able to regulate its own internal temperature. It will start to short cycle, leaving the temperature in your home cold because it does not run long enough to heat it. When the blower does run, it runs long after the system turns off, blowing only cool air through the vents. If you believe that the limit switch is about to break down completely, contact an HVAC contractor who offers furnace repair services to have them inspect the part to see if it needs to be replaced.

To find out more, contact a company like B & H Heating.