heating problems 318 is R Reg 1998

[cheat2one]

heating blowing cold air most of the time, temp gos up very fast
replaced the final stage resistor and the pollen filter, the heater is blowing air much better now but the heat is not there and the radiator fan is not kicking in too.
apart from this everything is ok, can anyone tell me what to check out or replace next ?

cheers

kevin.....................