Why is my capacator making a buzzing sound and vibrating when the fan starts.. is it normal or okay?

I would check to see if it is securely fastened to the unit. Perhaps it is simply mechanical vibration. If so, it's probably OK (I'd still tighten it). If it is something else, it's probably something to look into. How old is the condenser unit? Is the capacitor swollen? Replacing the capacitor is relatively inexpensive and might take care of the problem (if it is not simply loose).

Good luck,
WallyH

Capacitor? Sure it's not the contactor?

I agree with ma0641, never heard a cap buzz.

It's older. And definitely the round metal capacitor. Vibrating when the fan comes on. Only for 3 or 4 seconds.

Then it is probably loose in the bracket.