Oh No, My Furnace Fan Won't Stop Running! - Sun Heating & Cooling, Inc.

Oh No, My Furnace Fan Won’t Stop Running!

furnace keeps running

It’s cold out, and your home is nice and toasty. Everything’s perfect, right? Except your furnace keeps running … and running …

And running!

Has your system lost its mind or are you the victim of a ghost in the machine? Read on to understand the possible causes and solutions for an overactive furnace fan.

First, try turning your thermostat down and switching the system to “off.” If the fan keeps humming along, you likely have a stuck relay. This switch controls power between the thermostat and furnace components. A faulty relay can override your thermostat commands, telling the fan to keep on keepin’ on. Time to call in a pro like Sun Heating & Cooling to replace that pesky relay!

Next, inspect your thermostat batteries. Weak or improperly installed batteries cause all kinds of chaotic behavior like the fan operating constantly. Pops that Duracell back in firmly and your thermostat will regain control.

Older thermostats with mechanical parts can also get stuck in the “on” position due to grime buildup. Carefully wipe down contacts with a cotton swab dipped in rubbing alcohol. This can often get things moving again. Still fan-atic behavior? A new digital thermostat from Sun Heating provides a smart upgrade.

If the fan itself is running but not blowing any air, your blower motor could be burned out. Time for a replacement motor so you can get back to propelling those precious warm airs.

For homeowners with condensing furnaces, a drain clog can cause continuous fan activation. Built-in safety features turn the fan on to prevent flooding if condensate can’t escape. Clearing debris from the drain line does the trick, but, a repair of this level should be left to the experts at Sun.

And, what if your fan ISN’T running when it should be? That’s a whole other beast. Lack of airflow can lead to dangerous heat buildup and carbon monoxide. At the first sign of a furnace fan failure, shut the system down and phone Sun Heating & Cooling immediately. Safety first!

Has your heating and cooling system been acting weird this winter, by not turning off, or, any other strange quirks and issues? Contact us today if your fan won’t stop or start when it should, or give us a call: (248) 986-1506

Scroll to Top