Heating failure in Bizona Golf Vicizer V

It turns out that the bizona of my golf v 1.9tdi 105 hp when I put the heating the driver's side does not heat up, that of the perfect companion and the truth is that I do not know why, would anyone know how to tell me? I have reset the spracks but nothing, I have disconnected the battery, either, everything they have told me is unsuccessful, please help some