What does "blow hot and cold" mean?

Change one's mind, vacillate, as in Jean's been blowing hot and cold about taking a winter vacation. This expression comes from Aesop's fable (c. 570 b.c.) about a man eating with a satyr on a winter day. At first the man blew on his hands to warm them and then blew on his soup to cool it. The satyr thereupon renounced the man's friendship because he blew hot and cold out of the same mouth. The expression was repeated by many writers, most often signifying a person who could not be relied on. William Chillingworth put it: “These men can blow hot and cold out of the same mouth to serve several purposes” (The Religion of Protestants, 1638).