heater resistor and lights/alarm

i bought my 04 plate lh35 renault master last may, the fan has never worked only on full (number 4) just looked at the paperwork and 3years running it has had a heater resistor fitted, anyone point me in the right direction of what could keep making this go wrong? also (not sure if connected or not) i cannot put the fuse in for the internal lights without my alarm constantly going off only time it stops is when the fuse is out? any ideas? thanks!