I was driving to work when I noticed my temperature gauge going retarded on me. It would drop down to 100 when I was stopped. But on my way home I noticed it didnt work at all, it stayed on 100. When I got home I poped the hood and it sounded like I there was a vacumm hose loose ( I heard a strange hissing noise). So is there a vacuum that would cause that or is it something else?