7 Reasons Why Your Furnace Won’t Turn Off

November 20, 2022
Furnace in Beaumont, TX

When chilly winter nights arrive in Beaumont, TX, your furnace will cycle in order to maintain indoor comfort. In most cases, the furnace should run for a few minutes and then turn off for at least a few minutes until the next cycle begins. If your furnace starts up and won’t turn off, you might become worried about whether or not there’s a problem. Let’s take a look at seven possible reasons why your furnace won’t turn off and what you can do about each of them.

1. Dirty Air Filter

The most common cause of a furnace that won’t turn off is a dirty air filter. When the filter’s pores clog with dust and debris, the heated air can’t get through it. The heated air won’t reach your home’s living spaces, so the thermostat will continue communicating to the furnace that it needs to cycle.

2. Open Door or Window

Someone in your home may have accidentally left a door or window open. Consider a quick walk-through of your home to check for an ajar door or window. Even if a door or window is open just a few inches, it may be enough to allow cold air into your living space and hot air to leak outside. If you have been running an exhaust fan while cooking or cleaning, this functions like an open door or window. Hot air rises, and the fan disperses the warm air outdoors. Only run the fan for as long as necessary to prevent unwanted heat loss in the wintertime.

3. Wiring Issue

The wiring between your thermostat and furnace may have damage. This could lead to a miscommunication that keeps your furnace on. The furnace itself could also have a wiring problem. Although most furnaces burn gas for heat, the blower, ignition, and other components use electricity. Wiring issues require a professional repair.

4. Faulty Limit Switch

A faulty limit switch may keep your furnace in a non-stop heating cycle. The limit switch activates and deactivates the blower motor. If the limit switch gets stuck in the activated position, it will keep the blower going indefinitely. The blower motor may overheat. An experienced HVAC technician can determine if your furnace’s limit switch is faulty.

5. Thermostat Problem

If your home still has a manual thermostat, it may no longer work properly. Programmable thermostats may have lost their settings in a recent power outage. Your smart thermostat’s Wi-Fi connection may have dropped, or it may need a software update. Most thermostats are hardwired and have a battery to power the backlight. Faulty thermostat wiring or a drained battery also interfere with proper thermostat operation. Check the thermostat settings, replace the smart thermostat’s battery, and verify that your smart thermostat is connected to your wireless internet. If your thermostat won’t respond, an HVAC technician can repair or replace it for you.

6. Malfunctioning Blower

Your furnace’s blower may have an issue with the capacitor interfering with its ability to turn off. Other common furnace blower issues include loud noises, overheating, and an inconsistent fan speed. All furnace blower repairs should be left to an HVAC technician.

7. Leaky Air Ducts

Many homes have leaky air ducts. If the air heated by your furnace is leaking into the crawl space, attic, or wall voids, then it’s not reaching your living spaces. The thermostat won’t detect a change in the air temperature, so it will tell the furnace to stay on and heat your home. If your home has leaky air ducts, you might notice that some rooms are colder than others. You may even feel a draft in one or more of the rooms. When you put your hand over the air vents, you may barely feel a trickle of heated air coming out. An HVAC technician can check your air ducts for leaks and either repair them or make a recommendation for sealing or replacement.

In addition to furnace repairs, Reed Service Company also offers air conditioning repairs and heating and cooling maintenance, installation, and replacement. Beaumont area homeowners also count on us for dependable indoor air quality, geothermal, boiler, and HVAC design services. If you’re a business owner in or near the Beaumont area, our commercial HVAC services ensure a consistent and comfortable indoor climate in any type of commercial facility. For more information about why your furnace won’t turn off or to schedule a furnace repair with one of our prompt technicians, contact us at Reed Service Company today.