What are the signs of a cracked Serpentine Belt? Would I notice any noise or vibration in my car when the engine is running?
Usually a serpentine belt will not be noisy just before it snaps. Unless it begins to tear, and a loose end flaps against something. But, a good visual inspection can determine the need to replace. If the groove side has lots of visible cracks, and some missing sections of groove, it is time to replace.
If the belt is slipping and causing squeals, the problem is probably the tensioner, which should be replaced with the belt. This is to prevent the tensioner from going bad and ruining a belt before it’s time.
99 times out of 100, a bad, or badly worn, serpentine belt will give no symptoms whatsoever. It will just break. Then you lose your power steering and cooling system, and eventually your electrical system. You can inspect the belt yourself. If you see more than two or three cracks per inch of ribbed belt, it needs to be replaced. Also, if you know it has been more than three years since it was replaced, it should also be replaced to prevent a breakdown. It’s cheap insurance.
Perhaps you have not paid to have a serpentine belt changed lately, they can go $100.00+ parts and labor. Myself I would look for a aspect I can actually say is bad before going the safe but expensive route , changing simply by time in service even if all looks well