Possible Reasons Why Your Furnace Blower Runs Excessively

Alexandria, VA, homeowners often ask us why their furnace blower won’t stop running, even after the heater turns off. A functional blower runs for a minute or two before heating begins and for a minute or two after the heat cuts off. While the furnace is not running, the blower generally should not be running either. One exception to this is when you intentionally run only the fan to increase air circulation in your home.

What if the Fan Isn’t Set to Run?

In such cases, the furnace blower fan is usually not the problem. Rather, another component is malfunctioning and having an adverse effect on the blower. The source of the problem could be poor furnace maintenance, damaged wiring, a problematic relay switch, or a bad thermostat. All of these issues require professional heating repairs.

Poor Heater Maintenance

Thermostat problems caused by poor HVAC maintenance can cause a furnace blower to run all the time. Annual heating tune-ups that include checking the thermostat settings and testing and calibrating the battery prevent thermostat issues in almost all cases.

Dirty Air Filters

Clogged filters can limit system airflow to the point where no air gets through. Poor airflow can make the furnace overheat and cause components like the blower motor to malfunction.

Short Circuit or Broken Relay Switch

If the relay switch is broken or stuck, it cannot tell the blower to turn itself off. A short circuit or other wiring problem in the thermostat or near the fan limit switch can block those signals as well. If the relay switch is stuck, it might get unstuck a couple of times, but the problem will quickly return.

The blower might also run slowly or make clanking, rattling, or screeching noises. Those are all serious issues that can be prevented with regular furnace maintenance. Call the experts at Commonwealth Cooling & Heating. LLC before the issues can get any worse.