Heater help

If have a 2000 Bravada, a few weeks ago the heating system stopped working, or to be more precise, the heater blower doesn't operate.

I've changed the climate control unit and still nothing!!!! Have any of you guys had this problem? Also, any ideas how can I test the heater blower to check its function?

Any help is appreciated...I’m at a loss here!

Cheers

Stu