Fan blower ticking

I've been driving my recently purchased 1.9TDi Elegance for a week or so now and loving it very much, but coming home tonight with the climatronic fan blower set to level 4 I could hear a sort of ticking noise which appears to come from the left hand side of the dash. It sounds a bit like a dry leaf caught in the vent but the noise disappears completely at fan setting 3 so I don't think it is. I have read about the clicking from the climatronic flaps with the ignition on and engine off but I have heard this and the noise I have is different. Any ideas anyone?!