scenic 1.4 O4 plate, heater not working?

I have a Scenic 1.4 04 plate, the fan has packed in on 1,2 and 3 and only works on 4, after reading through it sounds like it is a common fault, is there a detailed way it can be explained on how to fix it myself, as i see the renault garage charge the earth, as will the other garages i suspect, so I am hoping to repair it myself, I have a Haynes manual but it doesnt really explain on how to repair this fault, as it sounds like it is the resistor which is at fault, so any detail explanation will be gratefully recieved many thanks
mandie