What could cause a replacement A/C condenser fan motor to only run for 3 minutes?
I had a capacitor replaced once.  Everything seemed to work fine, until 5 minutes after the a/c guy left, then the fan overheated and stopped.  I couldn't get him to come back, so I investigated and found that he hooked up the wires to the capacitor backwards; the fan was connected to the "run" prong on the capacitor and the motor to the "fan" prong.  I switched it back and it's been running fine ever since.