Certainly run capacitors do go bad but not nearly as often as the start cap does. Be sure to turn off power before starting to work on the unit at the circuit breaker and tape it off so someone does not hot it back up while you are working on it. Remove the shroud and the cover on the side of the roof unit. Be sure to short out the terminals of the capacitors to each other in case there is any stored voltage in the capacitors. There is not polarity on capacitors but you may find a dual capacitor that feeds the compressor and the fan motor. One terminal will be common and then one is Fan and one is Herm (for hermetic compresor). Be sure to wire new capacitor in this case properly. Reassemble the unit and turn the power back on.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7