Humidity

An air conditioner of this type always has standing water sitting in the base-tray of the machine as it's running. They're designed to work that way.

However, if the unit leans slightly in toward the inside of your house, then the water in the tray can be deeper than it should and/or add extra humidity to the inside air.

These units are designed to be installed so that they lean slightly to the _outside_ of the window or wall-hole where they are mounted. This way the standing water drains off to the ground outside and isn't so deep on the inside of the unit that it adds too much humidity to the inside air.

Check the mounting of this unit to make sure it leans slightly toward the outside. Also verify that any notch or drain hole on the outside end of the unit, intended to guide draining water, is not clogged with debris (which could also cause the standing water in the unit to be at too high a level).

Also verify that the "vent" is closed, if this unit is equipped with said vent opening. An open vent panel can allow humid outside air inside as the unit is running.

Hope this helps! ;)