How to Tell Whether Your Mac Fan Is Brokenby Katherine Harvey
Like the vast majority of computers, Apples are cooled by fans. MacBooks, MacBook Pros and Apple desktops all rely on fans to ensure that the computer doesn't overheat and burn out the motherboard, speakers and other assorted electronics inside your case. Because of this, it is imperative to know whether your fan is functioning correctly or is broken and inoperative. Close observation can tell you whether it's working.
Hold your hand next to the heat vents. On a desktop model, the vents are on the back, near the top of the case. On a MacBook or MacBook Pro, the heat vents are on the bottom of the case, in the crease where the screen folds down. If you feel heat flowing out of the vents, your fan is blowing heat out.
Press your ear to your Mac's case. With either a MacBook or MacBook Pro, you should press it to the bottom of the case. If your fan is running, you hear a quite whirring in the case.
Feel the bottom of your case. During normal use, your Mac's case becomes very warm. If your fan is broken, the case becomes extremely hot.