If you have a 10 mfd Fan capacitor and you replace it with a 5mfdand the voltage is the same will it work ?

Question

every thing else is the same except the MFD what will happen

Answer 1

I don't know what a fan capacitor is, but it probably won't do whatever it was designed to do.  The voltage rating is simply the maximum voltage condition under which the capacitor can operate.  Otherwise, it's meaningless for whatever job it's doing.

Capacitance is a measure of its capacity to hold a charge, but more importantly, its 'resistance' to change.  It affects timing or reactance to frequency.  It might be, in your case, a range of capacitance is good enough, say from 5uf to 20uf.  (Mf is millifarad and that's one frickin' humongous cap!)  So a 10uf cap is good enough, and replacing it with a 5uf won't affect much.  Or it could be a fairly tight design and cutting it in half will radically alter the circuit operation.  Without knowing its purpose, I couldn't say.

If in doubt, replace it with the same value.  They're cheap, so why risk it?

Answer 2

You mean the capacitor is part of AC motor circuit to make the FAN  runs ? If yes, you must put the same value 10 mfd. A less capacitance like 5 mfd shall make the AC motor runs lower speed and less power to turn.

IF this 10 mfd capacitor is just a parts of electronic circuit. A 5 mfd shall still good enough to replace it without cutting too much performance.

Answer 3

It might, but you should maintain the same value that the fan was designed for.