The part(s) or condition(s) listed below for the symptom Humidifier fan not working are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
Try spinning the blower fan blade by hand. If the fan blade does not spin freely, replace the blower motor. If the fan blade spins freely, use a multimeter to test the blower motor for continuity. If the motor does not have continuity, replace it. If the blower motor spins freely and has continuity, make sure it is getting power. If the motor is not getting power, replace it.
Turn the humidstat to its highest setting and listen for a “click.” The clicking sound indicates that the contacts inside the humidstat are closing to provide power to the humidifier. If the humidistat is providing power but the blower fan still doesn’t work, the blower motor itself might be defective.