Do you know how to use a 12V test light or better a volt meter?
I would first check to ensure the fuse is good and should be located under the helm.
Next verify 12v is on both sides of the fuse.
Next verify 12V is on both sides of the blower switch when in the on position.
Then and you can do this first verify 12V is present at the blower it self and that the ground is good as well.
If 12V and a good ground is at the blower then the blower is bad and needs to be replaced which is a fairly common issue.
BTY call me Mike
1997 2400 SCR
5.7 Vortec / Bravo 2