I would find compressor manufacturer's data and extract the information from that. Or get a parts house book and see if it provides capacitor info with the model of compressor you're working with. Johnstone's catalog is good about listing start and run caps with the single phase comps, plus which start relay to use.
Electricity makes refrigeration happen.
Refrigeration makes the HVAC psychrometric process happen.
HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.
A building is NOT beautiful unless it is also comfortable.
Originally posted by cbd33 Is there a way to size run & start capacitors for compressors if you have a situation where there are no original capacitors?
Yes, but you need an oscilloscope, a good command of trig, the equations and time. That is what the compressor manufacturers do when they determine the correct capacitor sizes. Get the information from them.