2006 Chevy Trailblazer Fan Belt

Hello,

A good indication of a fan belt that is going bad and has the possibility of breaking is by looking at the ribs and if they are cracked across the ribs there is a chance that it will beak. Just how long before it does is pretty much impossible.

A diagnostic machine is not capable of diagnosing or seeing when it will break.

And your last question. It would all depend on what they were checking and if it was done removing the belt to check something or checking the Tensioner Assembly. If your belt was in that bad of shape, even if it didn't look llike it was, then attempting to remove or reinstall it it could be damaged or even break in the proccess.

.