1. ### The blower motor is not receiving enough power. The blower motor is the component of the furnace that actually moves the air through the ducts. If the blower motor is not receiving enough power, it will not be able to start up properly. This could be caused by a loose wire connection, a faulty capacitor, or a problem with the blower motor itself.
2. ### The thermostat is not set properly. The thermostat is the device that controls the temperature of the furnace. If the thermostat is not set properly, the furnace will not be able to turn on the blower motor. Make sure that the thermostat is set to the desired temperature and that the fan setting is set to "auto".
3. ### The limit switch is tripped. The limit switch is a safety device that turns off the furnace if it overheats. If the limit switch is tripped, the furnace will not be able to start the blower motor. Check to see if the limit switch has been tripped and, if so, reset it.
4. ### The blower wheel is obstructed. The blower wheel is the part of the furnace that actually blows the air. If the blower wheel is obstructed, it will not be able to move air through the ducts. Check to see if the blower wheel is obstructed and, if so, remove the obstruction.
If the blower motor still does not start after checking all of these things, you may need to call a professional for assistance.
