Have a.O. Smith mod F48K92A01 fan motor and it runs for a few hours and then shuts down with the compressor still running. I wait an hour or two and turn back on the AC bang the top of the motor and it starts and runs for a few hours.
This has been going on for a week and now the motor does not start at all even after letting it cool down or banging on it. Please let me know what to do, tks

You will need to bang harder. Seriously, it may be dirtycorroded/burnt contacts inside the motor.

Maybe coroded connections on the Capacitor?
Went to the AO Smith Company to check motor design/parts, but like many large companies, they lose or don't keep track of, GE is another:
A.O.Smith Electrical Products Company (http://www.aosmithmotors.com/search.aspx?Q=%20F48K92A01)
Could be an overheat switch not resetting.

Have a A.O. Smith mod F48K92A01 fan motor and it runs for a few hours and then shuts down with the compressor still running. I wait an hour or two and turn back on the AC bang the top of the motor and it starts and runs for a few hours.
This has been going on for a week and now the motor does not start at all even after letting it cool down or banging on it. Please let me know what to do, tks

If this is a original factory OEM motor that came with the outdoor unit originally then the motor is probably defective by now. When you get a new motor make sure you get the original OEM motor OR make sure the motor you do get is equivalent in the following way. Horse power, voltage,physical size along with shaft length, direction of shaft rotation the motor spins (CW or CCW) and make sure you buy a new capacitor of the exact voltage and size to match the new motor. Most if not all residential condenser fan motors are of the 220/230 volt design but will work on 208 volts with a capacitor change of value. Check with your local vendor of HVAC parts or search the net using your outdoor unit model number to find the parts you need. If this is a bit too much to handle then please call a local HVAC company for on site service. But if you do it yourself pay special attention to the paperwork/directions OR the label attached to the motor for the electrical specs to be sure your new motor will perform as expected and provide a long life to the replacement motor.

Put in the new fan motor and capasitor and ran fine for the night. The next day it started the same problem.

I was thinking a centrifugal switch in first post, may not have, I see this is under AC? Oops

The problem was the fan was spinning the wrong way and also bypassed the delay control board as they do not use this board in newer AC's. Thanks for all your helping hands.