had the same problem, replaced the unit still no go, did a voltage check on the unit ok when ignition turned on but dropped to 6.5 volts when the engine started traced the red and black wires wiring that feed the fan control (change color the red wire becomes 2 blue wires) to the electronic box under the bonnet on the left the two blue wires go to the rear of the middle main plug removed the plug closed the gaps in the terminal a bit so there was good contact and the system now works fine just a bad connection only took about 4 hours of pain.
Trevor Guilford
October 2014