We were there in early August and while we were waiting in line to see some characters, we asked the CM that was accompanying the character where we might find a different character....I forget who we specifically asked about. If the character you are looking for is out in the parks a lot, those CMs accompanying characters can tell you where you will likely find them. But, if you want a definitive answer about a specific character, they told us to go to any location on WDW property that has a phone (i.e. a shop, guest relations, even a resort) and ask the CM at that location to call the "chip hotline" and find out if that specific character will be out today. We did do this several times and got good information.
Only the CM can call in for this information, and we were told that the hotline doesn't have the information available for the current day until 9am. Once the info is available, they will tell you which park (or parks) the character is scheduled to appear in, and the approximate time and location. If you are checking at one park, but plan to be at another park later in the day, let the CM know that, and they can ask the chip hotline if the character you are looking for will be at the other park when you expect to be there. Sometimes they cant give you a definite answer (we asked about Mulan when we were at MGM and we were told that a certain time and location there would be a number of face characters and Mulan might be one of them, they said they couldnt be certain because they didnt know her schedule)
.she wasnt there that day, but there were an number of other face characters there (and this was a character greeting that was not published in the times guide or park map). All of the other times we asked about specific characters, we were told when/where they would be, and they were there.