Blower settings 1,2 & 3 not working on Zafira?

I have a vauxhall zafira 2.2 design 2006 & the vents are not blowing any air out of settings 1,2 or 3. It only blows on setting 4. Although it is cold right now, it's just too much on setting 4 for a long period of time. Any suggestions what could be wrong?
Cheers