how do i fix the ignition on a peugeot 406?

I have 99(T) 406 petrol, had similar problem. When I have the cooling fan on full with a/c on, the ignition gets VERY hot seems too much current passing through it. Mine melted! I could not turn off ignition at all. Had to replace contacts on back of keylock which consists of plastic mounting and a number of wires only about 8 inches long, easy to replace but I don't know if this is a fault or a design flaw?

David Smith
July 2005