What Does a Furnace Limit Switch Do?

Call Fast Air Repair for high-quality heating and cooling services in Ocala, FL, and the surrounding areas! 

A furnace contains numerous internal components, but what does a furnace limit switch do? It is an essential part of a furnace because of its crucial role in temperature control. All HVAC systems have parts they cannot do without, and the limit switch on the furnace is important for several reasons.

Below, Ocala’s furnace maintenance experts at Fast Air Repair explain the importance of a furnace limit switch, including what it is, how it works, and why it’s vital to energy efficiency and safety.

What Is a Furnace Limit Switch?

Each component performs a specific function that allows a furnace to operate correctly. A limit switch is a relatively small internal component in a forced-air furnace. It typically consists of a temperature probe and an exterior plate, with some featuring a manual “On” switch that keeps the furnace fan running throughout the day.

While its main purpose is to provide your home with heat during chilly nights, a properly functioning furnace should also control temperature, work safely, and produce consistently low monthly energy bills. Unfortunately, this won’t happen with a faulty limit switch.

What Does a Furnace Limit Switch Do For The System?

A furnace’s limit switch works in conjunction with your thermostat to regulate the temperature inside of your furnace (and throughout your home). 

• When you set your thermostat to a desired temperature higher than the current indoor temperature, the burners inside your furnace heat up. 
• Upon reaching that level, the furnace’s limit switch will close, signaling the blowers to turn on. 
• The blowers then distribute the heated air throughout your home, raising the temperature.

Once the furnace sufficiently heats your home, the furnace burners turn off. However, the furnace limit switch will keep the blowers running until the furnace’s internal temperature decreases to a safe level. When it is cool enough, the limit switch will open and disconnect the circuit.

Why Is a Furnace Limit Switch Necessary?

A furnace limit switch is essential because it operates as a safety device under high temperatures. Without a properly functioning limit switch, your furnace won’t cool after heating your home. If it overheats, the internal components suffer damage and it could present a fire hazard.

The furnace limit switch also provides temperature control, leading to increased home comfort. It works with your thermostat and furnace, receiving and sending signals to heat your home and eliminate any cold drafts.

Finally, the limit switch keeps your furnace running efficiently to reduce your monthly energy costs. It does this by preventing the furnace from running for too long or heating a sufficiently warm home. Without a functioning limit switch, your furnace will work too hard and heat inefficiently, so you will quickly notice spikes in your monthly utility bills.

Furnace Limit Switch vs. Furnace Pressure Switch

What does a furnace limit switch do compared to a furnace pressure switch? It’s easy to confuse the two, as they look and sound similar. However, these two components have different functions. 

• A furnace limit switch deals with temperature.
• A pressure switch handles negative pressure inside your furnace.

Common Furnace Limit Switch Issues

With so many working components, numerous issues can affect the furnace limit switch. The most common furnace limit switch problem is a malfunctioning sensor. Professionals like Fast Air Repair can clean the sensor during maintenance by removing any dirt, grime, or debris.

Other common furnace problems that may affect the limit switch include the following:

• Faulty gas valves
• Broken or malfunctioning thermostat
• Bad circuit
• Dirty furnace filters

How to Tell if Your Furnace Limit Switch is Broken or Malfunctioning

If you notice the above issues, it is vital to call for professional help from local teams like Fast Air Repair as quickly as possible. A broken limit switch will mean the furnace fan will likely either run non-stop or not turn on. If either of those things happens, it could spell trouble.

Can I Perform DIY Furnace Limit Switch Repairs?

Unless you have professional HVAC experience and training, you need professionals like Fast Air Repair for a safe furnace repair service. With so many internal furnace components, improper maintenance or repairs can worsen existing issues and create more severe problems. You could also risk fires, carbon monoxide leaks, and other issues.

How can you prevent your furnace from overheating and keep it running smoothly? Our team would start by cleaning and replacing the furnace filters because dirty or clogged air filters easily cause overheating and internal damage. We advise replacing your furnace filters at least every three months to ensure proper operation.

What does a furnace limit switch do when the batteries in the thermostat run low? If there is a weak signal between your thermostat and furnace, or the furnace fails to heat your home to your desired temperature, there could be low thermostat battery power. In this case, replacing your thermostat batteries should provide an easy maintenance solution.

Furnace Maintenance and Repairs

If you notice any signs that your limit switch or another furnace component is malfunctioning, it is best to call HVAC experts like Fast Air Repair for professional furnace maintenance and repairs. Catching issues early makes things far more affordable, and keeping the system as efficient as possible will also lower monthly energy consumption for savings.

A professional team will quickly restore your furnace’s function and provide the maintenance it needs to keep running smoothly throughout the year. With expert HVAC technicians, you also have access to extensive industry experience, knowledge, and the right equipment to diagnose furnace issues for more comprehensive solutions.

What can you expect from furnace repair services from a team like Fast Air Repair? We are quick to respond to your call and can resolve big and small issues to restore your safety and comfort. We also offer 24-hour emergency services for safe and happy customers in and around Ocala, FL.

Scheduling regular furnace maintenance will also help to minimize the need for emergency repairs. While Florida residents may not use a furnace for the majority of the year, it must provide warmth when you need it. Annual routine maintenance will include tune-ups, cleaning, and replacing faulty components to ensure the system works efficiently.

Schedule Furnace Limit Switch Service from Fast Air Repair Today!

If you know how to monitor your furnace limit switch, you’ll know when to call an HVAC company for professional maintenance. A furnace limit switch is an essential internal component that contributes to temperature control, comfort, home safety, and energy efficiency. With a properly functioning limit switch, your thermostat and furnace work in tandem to heat your home efficiently and keep monthly energy expenses to a minimum. 

Hopefully, this article has given you a better understanding of what a furnace limit switch is and the issues that affect its function. With regular maintenance, the limit switch prevents your furnace from overheating to keep you and your family safe and warm through the winter. Whether your furnace needs repairs or annual routine maintenance for your heating system, you can count on Fast Air Repair for the following:

• Skilled and experienced HVAC experts who handle any repairs or replacements
• Great customer service from friendly furnace professionals
• A focus on energy efficiency to ensure you save more



What does a furnace limit switch do without professional furnace repair and maintenance? Don’t wait to find out; call Fast Air Repair at 352-290-7968 today for professional service in Ocala, FL, and the surrounding communities.