Alternator belt keeps snapping

Hello,

This could be due to a seized pulley or a stuck tensioner. If the tensioner exerts too much force on the belt it can snap.
A good first step would be to inspect all the pulleys as well as the tensioner. The idler pulley should spin freely as well as the tensioner pulley.
Make sure that the tensioner actually moves back and forth with appropriate amount of pressure.

Here is a helpful guide:

https://www.2carpros.com/articles/how-a-serpentine-belt-tensioner-works

Please let me know of any questions.
Thank you.