Take a stool if you have placed the air conditioning at a high end of the wall. Grasp the grille and pull it towards you. Then lift up the cover and remove the air conditioner filter, lifting the part of the equipment. Next you need to rinse the filter with warm water.
If your air conditioner has started to give bad smell, go to the market to buy a disinfectant solution. Apply it to the dry filter. These solutions usually are alcohol-based. However, most of the companies now offer air conditioners with plasma affect.
Open the lid of the machine, remove the dust grid, including spraying antiseptic solution so that the spray solution is dragged into the radiator. It will only take a couple of minutes and bad odour will disappear almost completely by using this procedure.
When the filter is dry, put it back on its place. Operating air conditioner without the filter is highly undesirable because it protects both your lungs and serves as the heat exchanger of the indoor unit. If the heat exchanger is dusty, the efficiency of the unit will significantly drop.
If you see water dripping from the indoor unit of the air conditioner, then most likely the drain line is clogged. Try (if possible) to get to the drain assembly and give a good blow into the drain pipe from where the water is dripping.