This is in my kitchen. The light switch on the left works a ceiling light directly above the switch. About 20ft over, there is a ceiling fan with lights on it.
The light switch on right turns the lights on to the ceiling fan. Only the lights.
The dimmer switch controls the actual fan, not the lights. If you turn the dimmer on just past the "click" the fan turns on and appears to work fine. If you turn the dimmer all of the way up, the fan continues to work, but makes an annoying humming sound similar to what a bad ballast in a florescent light sounds like. Turning the dimmer low or high does not change the speed of the fan.
What is the reason for the dimmer switch? Why was it used instead of a regular switch like the ones that control the lights? How difficult is it to swap out the dimmer for a regular light switch?