Q: Can a start capacitor be interchanged with a run capacitor?
A: Yes and no. In unusual circumstances, a run capacitor could be used as a
start capacitor, but the values available are much lower than the
values usually available for dedicated start capacitors. The capacitance
and voltage ratings would have to match the original start capacitor
specification. A start capacitor can not ever be used as a run
capacitor, because it could not handle current continuously (only a
couple of seconds).