Hi,
You should be able to get the radiator fan to come on ....
that is IF you have a properly working nice warm thermostat.
It should run around 180 F normally- and I think you said it does.
Cooler is not better btw .......if it's running at 160 F ........that is not right. Around 180, and even 195 in winter is about right. 

Assuming it runs at about 180 F ........just let it idle. It might take a long, long time with a diesel...
but eventurally, the temp will creep up .......and the fan should kick on.
I like to let them cycle on and off a few times, then you know for sure the fan, radiator, thermostat, and cooling system are all working right. 

I think you said you jumpered the sender contacts and the radiator fan runs like it should, right ? 
And now that you have a single, 3 terminal rad fan sender ( I just like 'sender' over 'sensor' personally ) ......two terminals jumpered should give one speed, and two other ones should make it run at a high speed. The middle pin, or terminal is not the one that's in common - one of the end pins is.
You jumper the wires that plug onto the sender of course. 
Scott
www.turbovans.com 
  ----- Original Message ----- 
  From: Alan Felder 
  To: Scott Daniel - Turbovans 
  Cc: vanagon@gerry.vanagon.com 
  Sent: Tuesday, September 01, 2009 5:32 PM
  Subject: Re: the case of the curious blinking LED

  Thanks Scott and David - I'm going to check out the starter switch and connections around it.  As part of this combination of jobs I also removed the last vestages of the Eberspacher wiring harness, so I was in that area and could have pulled something loose a bit.  I am not as worried about it at the moment because the temp now is steady and correct.  I recently checked the voltage stabilizer and it was ok, around 10.1 I think.  I tested the fuel guage during this whole debacle but should have tested the temp guage too.  I almost wish it would overheat so I could see if the fan kicks in.

  On Tue, Sep 1, 2009 at 2:38 AM, Scott Daniel - Turbovans <scottdaniel@turbovans.com> wrote:

    If I read this right .......
    you turn the key on to energize the glow plugs, and naturally, turning the key on makes the temp gauge LED flash a few times to tell you it's working.
    Then you turn the key to 'start' , it fires up, and the LED flashes again.
    I kinda wonder if that's normal even.

    Yeah, me too, but it wasn't doing that before.  So, better look into it.

  -- 
  Alan Felder
  Austin TX
  82 Diesel Westy