What are common problems with furnace blower motors?

Common problems with furnace blower motors include clogged or damaged filters, disturbing sounds coming from the unit, the furnace is on but does not produce heat and the unit turns on and off abnormally frequently. While these problems can affect any furnace blower motor, the frequency varies with the brand.

Dirt accumulation due to a lack of maintenance is the most common cause of faulty filters. Large particles also damage the filter, allowing dirt to enter the system. The blower motor makes humming sounds mainly due to friction or a damaged capacitor. The unit fails to produce heat for multiple reasons, including if the thermostat is damaged or the circuit is broken. A damaged thermostat also causes the unit to turn on and off at an alarmingly frequent rate.