Putting fans on dimmers causes strain to the fan motor because a fan takes 120v to operate and a dimmer only 90v. The motor strains to muster enough energy to get going causing serious wear on your fan. This house in Roswell shows a clip of the living room fan completely worn out due to being on a dimmer. The second shows the bedroom fan in the same predicament but still barely going. If you listen you can here the fan struggle to get up enough energy to operate. Without proper switching these fans will continue to need replacing about every year!