demisting

Hi All, Anyone else had issues with their windscreen demist setting on their Ibiza? Usually its really good, but this morning it suddenly stopped working, and instead the air started coming out from the sides...is there anything that can clog it up? Thanks.

I'm having a bit of trouble demisting my windscreen on these cold mornings.... When I hit the demist button on the climate control the fan speed increases as it should but there isn't the normal hot blast of air that there is meant to be, rather a hot trickle. I know it's cold so the...