Always be careful with resetting a circuit breaker. If it keeps tripping, then something is wrong! Reset it once and only once, and see if your unit runs normally.
Always reset a circuit breaker by ensuring that it is fully in the OFF position first (if not, move it there), then turning it back ON. Wait and see what it does after a few minutes of running. If the circuit breaker trips the second that your Hitachi AC turns on, then there is nothing more that you can do yourself
The reasons for you to regularly change your air conditioning filter are numerous, as are the benefits to both your health and the longevity of your Hitachi AC However, what you might not realize is that a clogged air conditioning filter can also cause your air conditioner's circuit breaker to trip.
Your Hitachi AC works by taking warm air out of your house, filtering it, then blowing the warm air over chilled coils called “evaporator coils.” These coils absorb some of the heat and then transfer it outside of your house, cooling the air inside of your house. If your AC filter is clogged though, the airflow to your unit is interrupted, causing it to work longer and harder than if it were a fresh, unobstructed filter. Over time, this can cause your AC to overheat and trip your circuit breaker.
For the same reasons as step one, you need to check your condenser coil. Once the heat that was removed out of your household air (in step one) gets outside, it has to be transferred into the outside air for the process to begin again. To do this, a fan blows outside air over the coil that is outside of your house, called a “condenser coil.” Make sure that this is free of dirt, leaves and debris. If it isn't, then clean it out with your garden hose. Again, think about this as your Hitachi AC having to run a mile; does it want to run uphill or downhill? Clean the coils and make it easier.
Low Freon or other types of commercial refrigerant can cause your Hitachi AC to work harder than it did before. A tripped circuit breaker can be a sign of this, so call to weather creators to solve this.
Over time and with the changing of seasons, wires will expand and contract, working themselves loose. An AC has an average lifespan of somewhere around 8-15 years, depending on your location and how well you've taken care of it.