My ac compressor trips the circuit breaker after it has started and ran for awhile. This is starting to happen about once every two days. I replaced the run capacitor and this did not cure the problem. When the compressor is not tripping the breaker, the unit cools properly (ie, it maintains the set temperature quickly, the air from the registers is appropriately cool). I installed a hard start capacitor and replace the contactors last summer. So they are fairly new. The circuit breaker has never tripped on start up. I usually notice the trip by observing the blower running and warm air at the registers.

Could be a weak circuit breaker.

Hard start capacitor,don`t last very long especially if the compressor is getting old ,tight,and hard to start,, may have to do it again