The serpentine belt (also known as the drive belt) is a reinforced rubber belt that delivers power from the crankshaft to multiple accessories of a vehicle such as the air conditioning, alternator, water pump, etc. Since it drives critical components of a vehicle, it is important to perform regular inspections of the serpentine belt and to replace it when it is required to do so. he replacement of the serpentine belt can be a quick and easy job if you are aware of a couple things that could possibly throw you off-course.