If the condener is making a humming sound it is probably a bad start capacitor.

Could be low on charge if it has a low pressure cut-out (then again, it could be almost anything).

Could have a bad contactor. Maybe its not pulling in all the way or there is a restriction between the contacts. (pitting, insects, debris). Voltages also need to be confirmed at the contactor by a trianed person. Capacitor needs to be checked as well. Don’t attempt to diagnose it yourself if you don’t know what you are dealing with.