I installed two Hunter Bay San Marino 36" ceiling fans with lights. They both work fine, except there is a noticeable motor hum when the fan is turned on low and gets noisier when switched to medium and high. Will low 110 VAC do this? Thank you. VChang

No, it needs vibration isolation. Try adding some paper and/or rubber washers between the blades and blade brackets, brackets and motor, and the motor and the ceiling.

See: http://www.ceiling-fans-n-more.com/ceiling-fan-general-troubleshooting-and-FAQ.php#6

That's a poor answer. Vibration is vibration and hum is hum caused by the magnetism that develops in the laminated plates of the stator.

To prove that vibration is not the problem, you can hold a fan blade still and turn on the fan and it will still hum without even moving. Point made.

The most common cause of a humming noise from a fan is the use of an improper speed control