What could be causing our air conditioner circuit breaker to keep tripping?
Too small a temperature swing on the thermostat can cause this issue as well.  Many electronic thermostats have an adjustable temperature swing of 0.5, 1, 2 degrees.  If this value is set too low and the compressor is restarted too soon (less than 10-15 minutes) after a cycle, it can trip a breaker as the compressor struggles to start against a pressurized system.  This setting is also known as differential, anticipation, or hysteresis.