Run capacitor how can i tell if the run capacitor is good

If the motor starts and runs the capacitor should be OK.
Disconnect power, discharge the capacitor (if there is a spark noticed when discharging it it may be OK)
Inspect the relief port to see if it has relieved pressure (some capacitors).
Isolate the capacitor from the circuit and check it with a capacitor tester. It should match the capacitance rating on the capacitor (MFD). Or if you do not have one measure the resistance with a VOM first one way, then reverse the leads and measure the resistance the other way. If the meter goes high and then low that capacitor may be OK. A failed capacitor may show an open circuit or a short circuit, but one that has some capacitance left will kick the meter. without the capacitor tester you may not know if the capacitance is still as rated. It is not that expensive and if there are no other problems replace the capacitor

Try this guide :)