Ducted air conditions require very little maintenance. Below are the few things you need to do in regards to regular maintenance for your ducted reverse cycle air conditioner.
The return air grille is the big grille (usually located in the hallway). It should to be cleaned as needed.
To clean the filter you need to pull back the clips or turn a screw and the grille should pivot down. Then you can vacuum the filter whilst still in the grille or you can remove the filter and either vacuum or clean with soapy water. If you clean with soapy water, remember to not dry in the sun as this will cause the filter to warp. If you are at all unsure how to clean this grille, please contact an air conditioning professional for assistance.
If the return air grille of your air conditioner becomes noisier than usual, or the air conditioner cools/heats less than normal it is a good sign that the filter needs a clean.
If you have health symptoms of constant headaches, fatigue, runny nose, dry eyes and a sore throat when running your air conditioner, it can mean 2 things. Firstly your filter may need a good clean (see above). Secondly, your ducting may be contaminated with dust and germs and may need to be professionally cleaned. Certain air conditioning contractors can professionally clean and remove the bacteria from your ducting, bringing your system to a healthy state again. This is the basic maintenance required indoors for your air conditioning system.