If a unit is too big for the room, it will cause the unit to short cycle, which means the output of the unit will ramp up and down too frequently. This can lead to fluctuations in room temperature and excessive noise. As a guide to finding what size air conditioner you need, you can use the Fujitsu Economatch tool, however, the best way to find out what size air conditioner you need for your room or home is to contact one of our Fujitsu Authorised Partners. Our Fujitsu Authorised Partners are able to assess your space and determine the best unit for your needs based on your requirements.