Have a central air unit. We run the unit for several hours and then the out side fan stops running , blows the breaker, and of course the blowing air in side starts getting hot.
Have had several techs out the last one replaced the contacts, and put a start kit in for the condenser, and we put a new thermostat in. and then replaced the breaker that keeps blowing.

It is still running for several hours and still cutting off, blowing the breaker.
It is one of those things that when the teck comes out everything is working fine,
The tech says the compressor is fine.
Any suggestions?
Could it be the capacitor or the Fan motor blowing the fuses?

It is possible the capacitor is breaking down. They are cheap & easy to replace. Other than the capacitor the problem could be either the fan motor or compressor going bad. For the price of a capacitor, it's certainly worth a try.