Winter in San Diego, CA, is usually mild, and there are plenty of beautiful beaches to explore. However, when temperatures dip, you don’t want to come home to a malfunctioning furnace. 

Your furnace may be malfunctioning because of an issue with the furnace limit switch. Discover the role of this vital component, how to tell if the limit switch on your furnace is bad, and more from the experts at Comfort Bros. We provide prompt repairs to help customers avoid additional and more costly issues. Understanding the role of the limit switch will help you find quicker solutions to your furnace-related woes.

Common Reasons Your Furnace Shuts Down

If your furnace keeps shutting down before reaching the ideal temperature, it can occur for several reasons. Here are some of the most common reasons your furnace shuts down unexpectedly.

Dirty air filters

A clogged or dirty air filter can cause your furnace to overheat, triggering the limit switch, which turns the unit off. Overheating, reduced airflow, higher energy bills, and poor indoor air quality indicate that your furnace’s air filter might be the culprit. A furnace shutting off due to overheating is one of the most common causes. 

Thermostat issues

Sometimes, miscommunication between the thermostat and the furnace causes the system to shut down. Repairing thermostat malfunctions, calibrating the thermostat, or installing a new smart thermostat helps prevent future shutdowns and frustration.

Blocked or damaged ductwork

Any obstructions or damage in your ductwork may lead to overheating and frequent furnace shutdowns. It’s essential to get regular ductwork inspections, cleanings, and repairs (if necessary) to diagnose furnace issues. 

Limit switch malfunction

What is a furnace limit switch, and how does it work? This safety device is located inside the furnace and closely monitors the internal temperature. If the temperature reaches a dangerously high level, it triggers the limit switch to turn off the furnace to prevent overheating, a possible fire, and other significant damage.

However, a broken limit switch can also cause your furnace to shut off unnecessarily because it doesn’t “know” the actual temperature.

What Is a Limit Switch and Why Is It Important?

It’s important to know what a limit switch is and how a malfunctioning limit switch affects furnace performance.

The function of a limit switch

A limit switch is a safety feature designed to prevent overheating. When the limit switch sensor detects exceedingly high temperatures, it shuts the furnace off. The furnace limit switch is necessary because it plays a vital role in maintaining proper temperature regulation to prevent major damage to the furnace.

How limit switch problems affect your furnace

Furnaces should turn off automatically when the indoor air reaches a pre-set temperature, then turn on again when the temperature is lower. However, it isn’t normal when your furnace turns on and off frequently (a process called short cycling).

When the limit switch is faulty, it incorrectly signals that your furnace is overheating, causing it to turn off. This leads to frequent shutdowns and restarts, or short cycling. This could cause the furnace to turn off and stay off, leading to a cold home. Faulty limit switches may also cause the furnace to remain on, leading to overheating.

Signs You Need Limit Switch Repair Services

Knowing when you need limit switch repair services from Comfort Bros is key to preventing bigger issues. Here are some telltale signs of a bad limit switch on a furnace that homeowners should know.

Frequent cycling on and off

Also called short cycling, this indicates that your furnace limit switch is shutting the system down incorrectly and needs attention immediately.

The furnace is blowing cold air

If your furnace is blowing cold air and then shutting off, or if it’s just plain blowing cold air, it may be due to a malfunctioning limit switch. When this component stops working, it disrupts the furnace’s ability to properly heat your Southern California area home.

Your furnace is overheating

When your furnace continues to overheat and doesn’t turn off, it can cause significant damage. A stuck or damaged limit switch may cause the unit to severely overheat, resulting in a much more expensive and time-consuming repair or the need for an entire furnace replacement. 

Troubleshooting Furnace Shutdowns

It’s important to know how to troubleshoot furnace shutdowns to protect your furnace and maintain its efficiency. Follow these steps to help you troubleshoot furnace shutdowns yourself at home.

  1. Step one: Check for obvious problems, such as blocked vents, dirty air filters, or a thermostat malfunction. If you’ve performed the basic troubleshooting steps and still can’t identify the cause of the problem, call Comfort Bros for professional help right away.
  2. Step two: Diagnose limit switch issues by becoming familiar with the signs of a faulty limit switch. However, in most cases, professional expertise is crucial to ensure the issue is addressed and repaired safely and effectively.
  3. Step three: If your furnace continues to shut off, contact the furnace repair experts at Comfort Bros Heating, Air, & Plumbing. Our certified HVAC technicians will accurately diagnose and fix your furnace limit switch problem and provide prompt repairs that prevent further system damage. 

Call Comfort Bros Today!

If your furnace keeps shutting down, the experts at Comfort Bros will make a diagnosis using advanced tools to pinpoint the exact cause. We’ll carefully assess the situation to minimize the risk of fires or damage and ensure your furnace is safe and fully operational.

Check out our website to discover new specials and discounts to help you save, and contact us for all your essential HVAC, plumbing, and furnace needs today!

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