Just had my mate Tim play with my blower fan, found that there was current getting to it, cut n crimped 2 of the earth wires, a bit of extra fiddling with the switch and i have a working demister!!!!!
Had the car 4 1/2 years with this problem and now it works fine. Only bothered me if the motor was left outside overnight, particularly in winter.
Lets hope nowt else goes wrong to get left that long.
Thanks Tim.
Andy