The limit switch is a small part inside your furnace. But in spite of its small size, the limit switch is very important for the function of your furnace. If this part breaks, your furnace will not work properly, if at all, which means you will need to have the part replaced. Here's a deeper look at the signs of a bad limit switch and how your HVAC contractor can fix it.
Signs of a Bad Limit Switch
The function of the limit switch is to sense when the furnace is getting too hot, and then turn the furnace off in response. In other words, it is a safety-oriented part. It helps prevent house fires and the scorching of items around your furnace, as well as heat damage to other furnace parts.
If your limit switch stops working, then your furnace will often start turning on and off repeatedly. This is because the switch is wrongly measuring that the temperature is too high and is turning the furnace off prematurely. In other cases, your furnace might not kick on at all. Or, the blower unit might turn on and blow air into your home, but that air will be cool.
Dealing With a Bad Limit Switch
If you think your limit switch is broken, then call a professional HVAC contractor. This is not a complex repair for a pro to make, but it is beyond the capabilities of most DIY-ers.
Your HVAC contractor will need to remove the cover from your furnace and probably undo a few screws or bolts. Then, they will test your limit switch. In testing, they may find that the switch just needs to be reset, which is something they can do for you. Or, they may find that the limit switch has broken, which usually means that one or more wires inside of it have been melted.
If the limit switch is broken, the HVAC contractor can remove it and put a new one in its place. The part itself usually only costs a few dollars. However, it may take up to a few hours to replace the switch, so you'll also have to pay for that labor.
Replacing a limit switch is a relatively small repair and is usually worth making, even if your furnace is older. Without making this repair, your furnace will not continue to heat your home. If you have any additional questions, ask local heating repair services.