Furnaces are a staple appliance in many homes across Mukilteo, Washington.
Areas that face regular winters and colder seasons typically have a heating system, such as a furnace, to keep the home cozy and warm.
Therefore, it is essential that furnaces and other forms of heating systems stay in working condition all year long.
These furnaces have a limit switch – also called a fan limit switch – built in to help control the flow of heat from the unit.
But is the furnace limit switch necessary? Can you still use your heating system without a furnace limit switch?
Today, we’re going to explore more about what a limit switch is, what it does for your furnace, how to spot damages to your furnace limit switch, and more!
So stick around and keep on reading.
What is a Furnace Limit Switch?
Essentially, a furnace limit switch is a component that turns your furnace blowers on and off. Your furnace limit switch is also responsible for allowing warm air to flow through the air ducts to heat your space.
It is also responsible for stopping your heating system from overheating. Your furnace limit switch will automatically turn itself off if it senses that your heat exchanger is getting too hot.
Why is a Furnace Limit Switch Important?
Your furnace limit switch is the component that prevents your furnace unit from overheating and getting damaged.
If you allow your heat exchanger to get too hot, this can cause your heat exchanger to crack.
Cracks are the last thing you want in your heat exchanger because this is where the byproducts of combustion are stored.
These are toxic particles, and when released into your home, can pose severe health risks to you and the people living with you.
Plus, letting your furnace cracks get worse will eventually damage your unit, and trust us, you don’t want to have to replace an entire furnace. They can cost a pretty penny.
Your furnace switch plays the vital role of keeping the heat under control, so your unit can last longer, work more efficiently, and pose no threat to your well-being.
So how do you know if your furnace limit switch is faulty? Is there a way to prevent your limit switch from breaking?
Let’s talk about it!
Common Issues You Find In Limit Switches
Limit switches are essential for any furnace unit. They’re concealed inside the furnace to prevent them from getting damaged by outside forces.
But as useful as they are, they are not perfect.
There are some common issues furnace limit switches are known for and we’re here to talk about them. So let’s get started:
A Clogged Furnace Filter
As we have mentioned, furnace switches automatically shut off when they sense that your furnace burners are starting to overheat.
One known cause for your unit to begin heating up rapidly is a clogged furnace filter. This is because the warm air being produced by your furnace burners is unable to flow through properly.
This then causes ”tripping” because the temperature sensor in your limit switch will sense that the heat being produced has reached the maximum temperature inside.
To stop your furnace temperature sensor from “tripping” too early, we suggest that you regularly inspect and clean your furnace filters.
Overheated Blowers
Another issue a furnace fan limit switch may encounter is an overheated blower fan/ blower assembly.
As soon as furnace limit switches notice that the unit’s blower fan is getting too hot, it will deactivate your furnace unit before even completing the heating cycle.
Signs of a Malfunctioning Furnace Limit Switch
Much like the rest of your furnace, your furnace limit switch is made with sturdy material to last you through years of use.
But eventually, your furnace unit will need maintenance and repairs. Here are the signs that your furnace limit switch needs the attention of an HVAC expert:
Your Furnace Limit Switch Shuts Off
Your furnace fan limit switch will normally turn off when it senses that your unit is starting to overheat.
But a damaged furnace fan limit switch will shut off even if your unit has not reached the maximum heat limit.
Your Furnace Fan Keeps Running
Normally, you can solve your fan limit switch issue by switching the settings from manual to auto, so that it switches off as soon as your furnace finishes its heat cycle.
But if your fan limit switch keeps running even after your furnace is done heating up your space, then you might have to repair or replace it.
Your Furnace Switches On and Off
Your furnace fan limit switch should only shut off when you turn it off manually or your HVAC system has reached the maximum heat limit.
If your furnace limit switch keeps shutting off in short intervals, you might need professional service or a new HVAC unit.
How to Set Your Furnace Limit Switch?
Your high temperature limit switch is in charge of regulating your furnace blower. It stops your furnace from overheating, shutting off your furnace blower as soon as it hits the maximum heat limit.
This prevents damage and prolongs the life of your furnace.
But to do that, you will need to set the temperature your furnace high limit switch is supposed to “trigger” and shut off your furnace blowers.
Not sure how to do that? No problem! Here’s how you can set your high limit switch to the right temperature:
Step 1: Your Access Panel and High Limit Switch
Approach your furnace and slide off or unhook the cover to your access panel. This will expose the contents inside.
Look for a piece that looks like a small rectangular box. That will contain your furnace high limit switch.
It’s usually found near the top of your furnace inside the access panel.
Next, you will uncover the limit switch by sliding or lifting up the top. The high limit switch should be sticking out right beside the number dial you will use to set the temperature of your furnace limit switch.
Step 2: Set the Temperature
The temperature you set will depend on what type of furnace you have.
Check your user manual to determine how high you should set your furnace high limit switch. But if you can’t access your manual, you can set your furnace high limit switch to 100 and 130.
This will tell your furnace high limit switch when to switch on or off.
Don’t forget to set your safety shut-off temperature. This will prevent your furnace from overheating and getting damaged.
It is suggested that you set the maximum temperature to 200 degrees.
Step 3: Make It Automatic
No one wants to manually shut off their furnace every time they use it. So why not make everything automatic?
Locate the white switch inside your access panel. This will reset the limit control to automatic.
Give your furnace blowers about 30 minutes to adjust and respond to the new furnace settings.
Voila!
Of course, you don’t have to do all of these by yourself. It can be a little confusing to change the settings of your furnace, especially if this is the first time you’re using one.
Luckily, there are experts who can change your furnace settings for you. All you have to do is make a call!
There are skilled HVAC technicians who can help you set your furnace to the right temperature, as well as, identify and diagnose any potential issues.
The last thing you want is to mess up your furnace settings just because you want to set your unit to a toasty temperature.
Getting Your Furnace Limit Switch Fixed
So you’ve tried cleaning your furnace’s air filter, and you even tried to check for cracks and rust on your furnace’s surface. But your HVAC system is still “acting out”.
It’s shutting off even before your unit reaches the maximum heat limit and it’s even blowing out cool air.
Plus, you’re hearing these weird rattling and clunking noises from inside the unit itself. That can mean there is a piece inside your furnace that has come off and needs to be reattached.
What should you do?
First off, we suggest you shut down your furnace, then give your local HVAC technician a call. You need to see if your unit needs to be replaced or simply requires repairs.
Furnace limit switch repair is not something you can do willy-nilly as there are many parts, such as the control wires, that need careful and proper handling.
A malfunctioning limit switch is not something you can easily DIY at home. One mistake can damage your whole furnace unit and you wouldn’t want that!
You will need skilled HVAC technicians to check out what’s going on in your furnace’s internal components.
Investing in a professional service also means that your HVAC technician can spot and diagnose other issues in your furnace that are not visible from the outside of the unit.
For assistance with installing a new furnace, setting your furnace limit switch, or furnace maintenance:
Dial (855) 345-6161
Once you set an appointment with our team of professional HVAC technicians for all your furnace-related concerns, we’ll handle the rest!
