To ensure that your ductless air conditioners functions properly, it is important that you take good care of it. First and foremost it is very necessary to keep the filters clean. The filters are located in front of the evaporating coil behind the front cover. Some units have black charcoal filters which needs to be dusted off and often and exposed to sunlight for at least 8 hours after every six months. These filters generally last for two seasons.At the same time, cleaning of the outdoor unit is also quite important because the coil has a tendency to trap dirt and dust. However, you will just need a soft brush to clean it.