Here is the most accurate method to test a run capacitor.

Note: Extreme Caution must be taken when testing.

Works for single or dual run capacitors under load.
For dual capacitor

• HERM side Measure the voltage between HERM and Common and measure Amps on HERM wire to the compressor.
• Fan side Measure the voltage between Fan and Common and measure Amps on the F wire to the fan.