Ok I have just been to the Auto electrician that does a lot of euro cars. I told him what was happening and what I had done (replaced Compressor and fan). He says mmm I think you have the wrong fan. I told him then that yes it was a fan from a petrol model. He said that that would 100% be the problem.
So now I am confused as to what to do, Bigwave's seem to work with the petrol fan, but mine definitely does not.
I have looked at the schematics on here
Engine cooling - BMW WDS
Electric fan - BMW WDS
And compared them, the look a little different.... not to sure.
What to do, another fan is $521 from Schmiedmann
Are you sure yours works Bigwave? No warming up when sitting at the lights?