Set the fan speed on high except in very humid weather. When it's humid, set the fan speed on low. You'll get better cooling, and slower air movement through the cooling equipment allows it to remove more moisture from the air, resulting in greater comfort.
Hammering a nail close to the edge of a piece of a board may cause it to split. This problem can be solved by using the nail to open up the split, them filling the crack with glue. Wipe off any glue that runs over. Remove the nail, then clamp board as the glue dries. To avoid these splits in the future, use a drill to bore a pilot hold.