After your home's furnace has shut off, you may have noticed lately that the fan still continues to run. You may have double-checked the thermostat to make sure that it was not knocked out of the "auto" setting, leaving you to wonder what the reason could be for the blower to keep running.

If the heating element itself is off and the fan is still blowing, there are a couple of possible reasons why it refuses to stop. 

1.  Fan Limit Switch Is Either on the Wrong Setting or Malfunctioning

One possible reason why your furnace's blower fan continues to run even after the heating element has switched off has to do with the fan limit switch which regulates when the blower fan should come on and when it should turn off. This switch is typically located at the top of the backside of the unit and is usually clearly marked.

After finding the switch, make sure that it is not on the manual setting. If it is not and is set to automatic, there is a good chance that the switch is malfunctioning. If this is the case, it will need to be replaced by a repair technician.

2.  Thermostat or the Blower Itself Has an Electrical Short in Its Wiring

Another possible cause of your furnace blower fan's inability to switch off may have to do with the electrical wiring. If there is a short in either the wire running from the thermostat to the furnace or within the blower fan itself, it may not be able to fully send the signal to shut off the fan.

If there is an electrical short, it needs to be taken care of as soon as possible, since it could fry either the thermostat or blower, requiring that it be replaced. Since this problem is an electrical issue, you will need to have a qualified professional fix it.

If your home furnace's blower fan is continuously running and you have already checked that the thermostat and fan limit switch are not on a manual setting, the limit switch may be malfunctioning or there could be an electrical short in the wiring. In either of these cases, you will need to have a professional take a look at the heating system. Set up an appointment with an HVAC system repair technician in your area to have them thoroughly inspect the furnace and thermostat to find and fix the issue with the blower fan.

For more information, contact a company like Advanced Air Conditioning and Heat.