As an electrician, the base of the bulbs (A15,A19) is the same. The diameter of the top half of the bulb is 1/2" larger in the A19. If you have a "normal size" globe on your fan, then yes it will work. Google
All Compact Florescent & LED bulbs can be used with normal light switches, however only the bulbs labeled as Dimmable / Full Range Dimming / or something else like, that work with dimmer switches. I don't see anywhere that these bulbs are dimmable therefore they probably don't work unless the dimmer is in the full max on position.