When air conditioning should windows and doors be open?

Normally, no. If you are using an actual air conditioner, open Windows and doors simply allow for more air transfer to and from the outside, forcing the unit to run more, wasting energy. However, if you are using an evaporative cooling unit (otherwise known as a "swamp cooler"), you might be able to get more air to flow through the unit by having some (not ALL) other Windows open. Evaporative coolers tend to put a lot of humidity into the air, which is fine in drier climates, but not so good in, say, the eastern half of the US.