If I use 2.5 Uf capacitor instead of 2.25 Uf What will happen?

Generally, there is a pretty loose tolerance on these caps, so in my opinion you would be okay since the new one is only about 10% off. Obviously, you would be better off with an exact replacement, but if I were in your shoes, I'd try it.

Best of luck,
WallyH

Remember they need to be AC rated. CeilingFanParts.com Home (http://www.ceilingfanparts.com) is a good source.

Remember they need to be AC rated.
Good point! You cannot use DC caps in this application.

You're fine.

Ceiling fan capactors - troubleshooting and resources - Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-capacitors.php)