Condenser fan quits on a Goodman heat/air unit

I have an older Goodman heat and air outside unit. I can run the heat on it for awhile, sometimes 30 minutes sometimes 40 minutes and sometimes longer, but then the condenser fan just stops but the rest of the unit keeps running.

If I pull the main breaker outside by the unit and shut everything down, and then put the breaker right back in, it starts right up, fan and all, and runs fine for awhile, but it then does the same thing. I can also let it just sit for awhile without pulling the breaker and the fan will eventually kick back on and run fine, and does this cycle over and over the same way.

Any ideas what the problem might be?