AC's tend to build up a lot of mold which grows in the condensation and blows it around. People with sinus and allergy issues get stuffy and inflamed. This is why I avoid using the AC and prefer a fan along with opening a window.
ACs tend to dehumidify the interior space. If they're properly installed all the condensation will drain outside. For window-mount ACs, you may need to shim them to get them to sit at the correct angle. For split ACs, the drain tube needs to be angled to allow water to flow out through the wall.
Sigh. The water condenses on cooler surfaces INSIDE the AC unit and drains outside. This is why mold grows on the squirrel cage and the walls of the blower housing. Even happens on wall mounted split units.