5 Reasons Your Furnace Fan Keeps Running and How to Solve This Issue

April 4, 2023

It’s one of the most common problems homeowners face with their HVAC systems. If your furnace fan runs continuously, it may be caused by a few different factors. This article will explain why your furnace fan keeps running, what the causes are, and how to fix them.

Let’s take a look at 5 of the most common causes:

1. The Furnace Blower is Set “On”

The most common cause of a furnace fan running continuously is that the blower setting on your thermostat is set to “on.” This means that the fan will run constantly as long as there’s electric power. This will happen regardless of whether or not your furnace is actually heating. To fix this issue, you’ll need to change the settings on your thermostat. Just switch the fan setting to “auto” instead of “on.” This tells the system to only run the fan when the furnace is actually heating.

2. The Thermostat is Automatically Turning the Fan On and Off

Another possible cause of your furnace fan running continuously is that the thermostat itself is automatically turning the fan on and off. This can happen if you have an automatic timer set for when the system should turn itself on or off. Sometimes, it’s a smart thermostat that’s designed to turn on every hour or so to keep air circulating throughout the house. If this is happening, then you’ll need to adjust the thermostat settings so that it only turns on and off when necessary.

3. The Fan Limit Switch is in Manual Override Mode

In older HVAC units, the fan limit switch may be set to manual override mode. This means that the fan will run constantly until you manually turn it off. If this is the case, then you’ll need to find the fan limit switch and move it back into automatic mode. This will ensure that your furnace fan runs only when necessary and not continuously. The fan limit switch is typically located near the blower motor or in the control box. It just requires a press from your finger to behave accordingly.

Most homeowners find older HVAC units complicated to handle and they prefer to call in an HVAC technician when something isn’t working correctly. Before you do that, however, it’s important to check the most basic settings so that you can potentially fix the problem yourself. In this case, it may be as simple as adjusting the fan limit switch or changing the thermostat settings. That being said, if you’re not confident in your ability to diagnose or fix the problem on your own, it’s best to call a professional. They can inspect and repair the furnace quickly to ensure that your home stays warm and comfortable.

4. A Bad Thermostat

A faulty thermostat can cause your furnace fan to run constantly. Your thermostat should be checked for proper calibration, battery condition, and settings to ensure that it is working correctly. If you suspect an issue with the thermostat, try replacing the batteries or checking the wiring connections. You may also want to check the temperature settings on the thermostat. If you are still experiencing issues with your furnace fan running, then it is time to call in a professional for service.

5. A Bad Circuit Board or Shorted Wire

The circuit board or wiring in your furnace may be faulty, causing the fan to run continuously. This is a complicated problem that requires professional furnace repair. It is important to note that you should never attempt to repair these issues yourself as they can be dangerous and could reduce the longevity of your furnace system. A qualified HVAC specialist should be called in to diagnose and repair the issue.

Contact Carney & Son 72 Degrees For Furnace Fan Repairs

If you are still having trouble with your furnace fan running continuously, then it may be time to call in a professional for repairs. The team at Carney & Son 72 Degrees is here to help. Our experienced technicians have the expertise and knowledge to diagnose any issue with your system and repair it quickly, so you don’t have to buy a new furnace unit. Contact us today to learn more or to schedule your service appointment!

Carney & Son Air Conditioning and Heating

Carney & Son, 72 Degrees

We are a family Owned & Operated HVAC Services in Charleston, SC, proudly serving the Charleston community for 39 years.

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