The compressor on your freezer is designed to keep it at the correct temperature. If you notice your freezer is making a 'whirring' noise for extended periods of time, your compressor is simply working harder to keep it at the right temperature. To reduce the amount of time your compressor is active, ensure the ambient temperature is inside the recommended range for your freezer. Opening the freezer door very frequently or for extended periods can also cause the compressor to run for long periods of time, so keeping the door closed will allow the temperature to stabilise.