Engine cooling fan problem

[Lowflyingbird]

I have a 1996 E300. it's my second W210 diesel. Recently purchased, Been off the road getting alot of work done to it.
I had the car run in the driveway a long time after changing seals, lines, etc. It began to run EXTREEMLY hot, so it got the garden hose at the radiator treatment to cool it down. Conclusion, it needed a new mechanical fan clutch. That is now in and there is a huge difference. I strongly recomend anyone with a high mile car to change there fan clutch.
When I was thinking about it, the thought arose; Why did the electric cooling fans not kick on? I know that they work when the AC is activated. I thought when the engine got too hot they also turn on? I tried junping direct power to them and I got nothing. The electric fans were also dead.
I now have a new set of eletric fans in the car. NEW PROBLEM, when the engine is running the fans are on all the time. I unplugged them for now.

On a sort of related note. The climate control panel on the dash is no good. I can turn it on and raise/ control fan speed, but that is all. The display reads LO for temp and it always blows cold. I'm under the impression that the no good climate control is sending signal to the electric fan to constantly run?
Thoughts?

[okto]

Could be one of the temp sensors has gone bad. Try unplugging the engine coolant temp sensor. On my OM606 (95 E300D), it's blue/green and located in the front of the valve cover by the radiator hose. With the car running, unplug it and see if the fans run.

[piccolovic]

either that, or the relay switch