There are three main reasons you might be having problems with your air conditioner leaking water. The drains might be blocked, there might not be enough refrigerant or the heat-exchanging coils or filters are dirty. Here is a closer look at what to do in each of these cases but always keep in mind that calling in a professional is the best action to take. Also, make sure before you take a look that the power source is off.
If you have a ductless wall-mounted air conditioning unit then it is usually clear when having a blocked drain is a problem. The water will drip down from the rear of the unit down the wall outside and might even leak through the front too, out where the air comes through. If you get up above the unit and look down you can see if the air conditioner leaking water has a full plastic tray that is meant to catch condensation but can get full when there is a leak. You might find that if you have an outside unit that is behind the wall where you have the inside part mounted that there is water dripping from the drain pipe. Make sure the pipe is kept clear of debris and blockages and call a professional company to help if needed to unblock the drain.
Blocked or dirty heat exchangers or filters
The heat-exchanging coil and filters can get dirty or become clogged and that can affect the airflow and then lead the coil temperature to drop. If it goes below zero then the condensation on the coil can freeze and those ice flakes can cause leaking water. When you look at the filters they should be clean, if the dirt is building up, rinse them with a shower head or hose. Simple antiseptic spray can deal with mould and bacteria.
You or the professional you call to examine an air conditioner leaking water should also check the coils behind the filters. If there is a lot of lint carefully try removing it. If it is really dirty you could try some grease removing cleaner. Spray and leave it for a few minutes then rinse. You should notice an improvement in how the unit performs. Be careful of what and where you spray around the electronics.
If you have checked the filters and the coils and they are clean and you are seeing good airflow, but it is not cooling the room like it used to, it could be air conditioner leaking water because there is not enough refrigerant. You can test this by setting the heat pump to very low and letting it run for a while and seeing if the room cools as it should. If there is a leak like this you need to find it or call in a professional company to handle it and then the refrigerant will need to be replaced.