The indoor units of wall mounted split system air conditioners should be cleaned regularly to ensure optimum performance of the unit. We have put together a handy video that details the process for cleaning an indoor split system unit, which you can watch by visiting our air conditioner maintenance page.How often you need to carry out this cleaning process will depend on how regularly you use your air conditioner. If your air conditioner is in constant or daily operation, we recommend you clean the filter once a month. For units that are used less frequently, cleaning the indoor unit’s filter once every three months will be sufficient to maintain optimum heating and cooling performance.