Why is there sludge in the bottom of my wall unit a/c?

There is rust-colored sludge in the bottom of my wall unit a/c. The bottom coils are sitting in this watery sledge. I drained most of the water out but still have the sludge. What is this sludge and how can i clean it out? How can it be prevented from re-occurrring?

Why is there sludge in the bottom of my wall unit a/c?
Its a byproduct of the cool water always being present. You need to angle the unit so the water drains away as its created.
Reply:The "sludge" is a mixture of dust/dirt rust and algae. Slide the unit out of the wall and take it outside and give it a good cleaning with a garden hose. Remember to clean the condenser coils off as dirt builds up on the coils where the fan blows against them and slings the condensate water. Dump as much water out of the unit as you can by laying it on it's sides and even on it's top and then let it sit either in the sun or in the wall for a couple of hours to ensure that there is no moisture in the electricals.





You can prevent the algae from growing again by slowly pouring a cup of warm water mixed with a tablespoon of baking soda into the evaporator coils so it runs to the outside once a month. A good cleaning should be done every few years to ensure that the unit works to it's fullest capacity.
Reply:Many Ac units are designed for the condensor to sit in the condensate water to help cool it. You could spray this out with a garden hose or wet vac it.


You cannot prevent it for happening, but you could clean it every year. This would insure no condensate dripping into the house, as the drain holes would all be clear.
Reply:it sounds like dirt mixed in with the condensate, make sure evaporater and condenser coils are clean.
Reply:The sludge is dirt and condensation. you need to pull the unit out of the case in the wall and take out in the yard. Go to local hardware store and buy acid coil cleaner. GO back home and spray coil cleaner on all coils and wash out with water hose PS. DO NOT USE TOO MUCH PRESSURE ON COILS OR YOU COULD DAMAGE COILS. GOOD LUCK.