If you are experiencing the air flow of your unit not heating or cooling as it should be, the main cause of this would be dirty filters. It is recommended to clean your split system and return air filters every 3 months to ensure the units are always efficient. Split Systems – open the front of the unit, you will see the filters straight away, these are removable so don’t be scared to pull them out. Vacuum or wash under a tap to remove dust (Must be completely dry before re-installing). Carefully replace back into the unit and close the front. Return air’s – Carefully remove return air grille and take out the filter. Vacuum or use a brush to remove dust. Carefully replace filter back into the Return Air grille and replace grille back into place.