Help! Why Does My Furnace Fan Keep Running?

You rely on your furnace every winter to keep you and your family comfortable regardless of the outdoor temperatures. However, there are times when a furnace will run incessantly. It leaves homeowners asking, “Why does my furnace fan keep running?” as they shed extra layers of clothing, but what’s the solution?

You might need professional furnace repair in Richmond, KY, but to be sure, the Watson Heating & Air experts share seven reasons a furnace might be running all the time and what to do about it.

#1 You Set the Thermostat to ‘On’

If your furnace fan keeps running endlessly, the first check should be your thermostat settings. Have you set your thermostat to ‘on’ by accident? Many homeowners do this and start panicking as their furnace runs when it should be off.

It is best to set your thermostat to the ‘auto’ setting, allowing the furnace to power down once it reaches your desired temperature. Otherwise, the heat may turn off while the fan keeps going.

Do you have a smart or Wi-Fi-controlled thermostat? Certain models may keep the fan running by default. Locate the manufacturer’s manual to determine how to change the settings. 

#2 Your Thermostat Shorted a Wire

If you corrected your thermostat settings but still suspect an issue, you might have a shorted wire causing technical problems. The only way to safely check is to schedule services with a heating expert to solve this problem. Tinkering without knowing how wiring works could prove unsafe or exacerbate the problem.

#3 Your Limit Switch Setting Is On ‘Override’

Most furnaces come with a limit switch, a safety feature that senses whether or not the fan is rotating. Its function is to prevent the furnace from overheating during its heating cycles. If your furnace is in danger of overheating, the limit switch signals the system to shut down.

Like your thermostat, limit switches have two settings: ‘auto’ and ‘override.’ Auto is the preferred setting. If the override setting activates, the fan constantly runs, and you will need an experienced HVAC technician to locate the limit switch and check the settings.

#4 You Have a Faulty Limit Switch

If the limit switch is on ‘auto,’ but the fan still runs continuously, the limit switch may need replacing. A faulty limit switch poses a safety hazard since it can’t serve its normal function of preventing the furnace from overheating. Be sure to schedule services to replace the damaged switch before using the furnace again if you want to avoid the risk of fire or electrical problems. 

#5 You Need To Replace Your Furnace Filter

Why does my furnace fan keep running with a normal thermostat and limit switch? The next check is for a dirty furnace filter. This is one of the simplest problems to fix, and you’d be surprised how many people forget to change the filters every two to three months.

A dirty filter caked in dust, microbes, dander, or mold easily decreases indoor air quality. It also blocks airflow and forces the blower fan to work harder, causing higher energy bills.

#6 You Have Loose Ductwork

Your heating and cooling ductwork contains numerous joints and seals that loosen or crack. Even small fractures allow air to leak, preventing the system from maintaining your temperature settings efficiently. The furnace works overtime, blowing incessantly and wracking up energy consumption.

#7 Your Thermostat Takes Inaccurate Readings

If there’s still a problem, the final check is to go back to the thermostat. Is it near a window, door, or another drafty area? Bursts of cool outdoor air could affect your thermostat’s room temperature readings. If there’s a cool draft, the thermostat will always detect a cooler temperature. 

The result will be an uncomfortably hot temperature in the rest of the house, but there are several solutions. Firstly, try to locate where the draft originates and use caulk to seal nearby doors and windows. Secondly, enhance your window treatments to improve your home’s efficiency.

Did that work? If not, lower your temperature settings for now while you call us to reinstall your thermostat in a more suitable area.

Why Does My Furnace Fan Keep Running? Call Watson Heating & Air to Find Out!

Is your furnace giving you problems? It is time to schedule common furnace repairs with Watson Heating & Air. We work hard to solve all heating and cooling issues to restore the comfort your family deserves.

Why does my furnace fan keep running after I’ve checked all the points above? We can help you find out when you call Watson Heating & Air at (859) 659-7272 today!