bad wall switch for ceiling fan??

i have a 2 switch outlet....one toggle style for ceiling fan with light kit in the sunroom (it works fine)and another with a larger toggle style switch with a slideing dimmer attatched for another ceiling fan with light kit( sorry I dont know the names of the different styles? My problem is with the switch with the slideing dimmer....the light kit works fine but the fan hums and will turn at about 1 rev/15 sec......the wall switch also hums(can hear it 5 ft away)...should i try and replace the switch with a basic 2 station switch or is the fan shot..I dont have a voltmeter...replacement fan is $75 min...its been this way since i moved in and the kitchen gets darn hot in the summer....sorry for the way i explained my problem....hope someone can help thx