Q: serpentine belt keeps breaking

The belt is either too tight or too loose, pulleys (including that on the harmonic balancer), the tensioner, and accessories are out of plane, and/or the belt driven accessories are binding, that is they are not turning freely because the bearings are damaged or the grease is depleted or dried up. The best thing to do is schedule a belt inspection/diagnostic/replacement and the responding certified mechanic will determine which fault(s) exist, estimate the repair for you and, with your permission, perform the repair. Other less common possibilities include being given multiple defective belts and the presence of significant oil and/or antifreeze contamination of the belt. In the event that the belt is not operating freely due to binding pulleys, there could more than one such pulley that would have to replaced. Obviously, the mechanic would show all defective parts to you and explain in detail what the fault is.