I have been asked a few times about wiring up a single capacitor when a dual round has failed.
First of all I dont suggest doing this and it is a quick fix when you dont have the correct dual round capacitor with you.
With that said this is done all the time by HVAC technicians and you may find yourself working on a unit that has been fixed this way.
Wiring up a single capacitor is easy if you simple remember that a dual round is two capacitors in one package.
The common Leg is shared while the other legs go to there separate components.
Since a dual round shares the common leg there is only three connections. A jumper wire will need to go to the common leg on the single capacitor.
Since they are two capacitors in the same package they can be separated into single units.
Often what happens in a A/C unit is one side will fail while the other is good, so a tech will simply wiring a single to replace the bad side.
For example most all dual rounds will have a capacitor for the compressor and one for the condensing fan motor.
If the compressor side capacitor in the dual round is good but the fan side fails, the fan side can be replaced with a single.
Since the compressor side cap is good it will stay connected and working.
Wiring in a single capacitor to replace a dual is easy to do with some basic understanding.
A jumper wire will need to be installed to carry the common wire to the added capacitor since a dual round will share this leg.
Also be sure to match the MFD and voltages to the correct components.
Remember always install the correct components unless you have no other options.