The blower fan inside your furnace is responsible for circulating the air in your entire home. Some homeowners may not want this fan to run when the heat is not running so that the system is more energy efficient. However, you may find that the fan is running at all times and you want to get to the bottom of it. Here are some quick ways to troubleshoot a constantly running blower fan:
Check Your Thermostat
You should start by checking your thermostat's settings to determine if that is causing the blower fan to always be on. You may be surprised to learn that the fan controls are located in an odd place, especially if you have a digital thermostat that is controlled with an app. It is not as easy to figure out as looking to see if a switch is flipped.
For example, the Nest smart thermostat app has a setting where you can allow the fan to run for a continuous period of time, but it is limited to a certain amount of hours before the settings go back to normal.
There is an additional setting hidden under the settings where you can set the fan schedule. This is different from the heating and cooling schedule that you set up in the main thermostat settings. You may have unintentionally set the fan to run non-stop without even realizing it back when you were setting up your thermostat.
Check Your Air Handler
While your furnace has a main purpose to warm up your home, it also has a job of filtering the air. The filter inside the blower is responsible for trapping dust and mold particles, which removes them from the air during normal HVAC system use.
There is a way to use the blower for filtration purposes by overriding settings at the air handler. It allows the fan to run continuously even if the HVAC system is not on. Open the air handler and look for a switch mechanism that operates the blower. When activated, the fan will run continuously even if the thermostat says otherwise.
There may be times that you want the blower to run, such as times when it is not cold enough to run the furnace but you do want cleaner air. Now that you know where the switch is, you can intentionally turn on the blower fan when you are ready to do so.
Is the fan still running even after checking these two things? Contact a local HVAC repair service like HELP Plumbing, Heating, Cooling and Electric for assistance.