Need help with Air Conditioner / Hard Start Capacitor issue

Without getting into heavy duty theory here--starting capacitor sizes are picked to function with a certain motor depending on the internal resintence of the starting windings,it's wire size and etc, etc. So too much capacitence is as bad as too little.
So adding the capacitor is probably taking it too far from it's
optimum value.

I also don't see the PTC motor starting device in your second picture. This needs to be in the circuit also.