Hevac problem

Hi all I have a 4.0ltr P38 and the Hevac is puzzling me. Everything lights up as it should but heated front and rear screens don't light up or work and when I try to change the air distribution from feet to side vents the relevant button lights up there is no change in air distribution it's as if its coming out all areas windscreen, footwell etc. is there a relay that would cause this issue ? I've checked all the fuses they appear ok.

heated screens maybe a relay,your air distribution is probably down to blend motor(s) is the cheque book symbol on on the hevac display??

Thanks Clarkie I get the cheque book icon if I turn on aircon but normally no it doesn't appear.