How to Stop Boat Air Conditioning Systems From Sucking in Mud

Open the hull door that provides access to the water filter.

Turn off the seacock -- a valve typically found on the boat̵7;s hull -- if the filter is mounted below the waterline. This prevents water from flowing into the filter while you work.

Remove the basket strainer from the housing.

Scrub and remove excess or hardened mud lodged in the strainer. Use a toothbrush.

Empty mud from the strainer and rinse it with water.

Insert a water hose into the line connecting the filter; flush the cooling system. Most docks are equipped with water hoses.

Drop two bromine tablets into the basket before mounting it. Bromine helps keep the lines clear.