My ac unit condenser fan not working,I have to push manually,then it run & after 10-15 minutes it stop again, please help me.

You might try replacing the fan motor capacitor. If that does not work you will need to replace the motor.

I put new motor & capacitor in lennox A/C condenser,still
My ac unit condenser fan not working,I have to push manually,then it run for 10-15 minute & stop,compressor make noise for a little while,then main switch tripp.

The motor is wired incorrectly OR you did not replace the old capacitor with a new one sized for the new motor OR the new motor is spinning the wrong direction.