blowers freezing cold on ford ka T reg?

how do i fix my blowers, permantly blowing out freezing cold air, as if you have it on setting 2 and on cold, thats for 1 and hot :|(suppose to be hot), i checked coolant level its still at max, but on the very odd occasion it wants to kick out warm air but can't, my mate suggested its a blockage in the matrix pipe and put water in to remove it, but i dont know where the matrix pipe is, so any help would be fab, my ka is a 1.3 t reg (1999)