Tech Support’s Biggest Fan

(I work in IT, supporting other employees at my company. I have received a ticket from one user complaining that his computer fan has completely jammed, and has stopped working entirely. As this is a pretty serious problem, I hurry over. When I get to his desk I see that his computer is on and the fan is running, although noisily.)

Me: “Oh, your computer’s fan isn’t jammed. It’s just running with a little more difficulty than usual. It probably needs to be cleaned.”

User: “What? How can you know that? You haven’t even opened up the computer to look.”

Me: “Well, if your computer’s fan had really stopped working entirely, your computer might be on fire.”