Central air system turned on, condenser fan and compressor not running. Reset button is tripped. Press reset , contactor closes compressor motor starts, condenser fan does not start. 20 seconds later reset trips shutting down compressor. Same result even after letting sit overnight. Old Williamson unit with schematic washed out. Is the non working condenser fan causing the compressor to shut off?Cannot find (visualy) any leaks in system.

Most likely the compressor is overheating and shutting down due to the fan not working. Just need to determine if it's the fan motor, the fan motor capacitor, or power to the fan motor. If you give the fan a little push when it should be running, does it take off then? Im betting you need a new fan motor or capacitor or both. If the fan blade is stiff at all to turn by hand, a new motor and matching cap it is.