As thermostats do for the entire unit, the energy-saver feature will cycle the compressor on and off so that it doesn't operate continuously. You don't have to know whether the compressor is on or off as long as you are aware that the energy-saver feature will reduce your energy expenditure. Your personal comfort also is important. Using a thermostat in conjunction with the fan speed allows the user to bring the room temperature down to the desired comfort level very quickly. The fan can be adjusted to a lower speed to maintain the temperature.
All air conditioners have a filter.
However, for easy maintenance, select a model with a slide-out filter. When it comes to the temperature control or thermostat, digital models are the easiest to use and the most precise. Some models are equipped with a timer that allows you to set the air conditioner to begin cooling any time - whether you are home or away. The price range is as broad as the choices. The cost is determined by many factors - the size, make, features, efficiency, etc.