4000 dual-fan conversion done

[Ti Kan]

Hi all,

Another progress report on the R134a A/C conversion project on my 4000.

I have completed the conversion of my early 4000 4-cylinder single radiator
fan to the later dual-fan setup.  After refinishing the used fan shroud,
fan housings and fan blades to like-new condition, I installed a new
belt (there is one motor that drives the active fan, the other fan is
belt-driven from the active fan).  Everything just dropped right in
with absolutely no modifications needed.

In fact the fan motor is a lower wattage than my original fan, so it
runs much quieter and puts less load on the electrical system.  My old
fan was a 150W unit whereas the "new" fan is 100W.  With engine up to
operating temperature and idling, the radiator fan would cycle on as
expected, but now the "on" time is much shorter than before, so it
indicates that the dual fans cool much more effectively than my previous
single fan.

Instead of the loud fan motor roar, the new setup is virtually whisper-quiet.
With the lower current draw, it means less load on the alternator, which
also translates to less load on the engine.  This are all very welcome
improvements because on the 4000, there is only one fan speed and on my
early model the fan runs continuously when the A/C is on.  The increased
flow from the dual fans through the condensor should also improve A/C
performance.

So, I am very happy with this swap.  Next up on my list (and the conclusion
of my A/C project) is the addition of an idle-boost valve that opens when
the A/C compressor clutch is engaged.  Later model 4000s and other Audis
have this, but mine doesn't.  My idle speed would drop a bit when the A/C
compressor kicks in, and this is just a bit annoying.  I will report on
that when I'm done.  It should be very soon now.

-Ti
P.S. Many thanks to everyone who responded with suggestions about my
     query for a T-piece.  Special thanks go to Avi Meron and Huw Powell
     for their trouble of actually sending me pieces.
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti at amb.org
 //////  http://www.amb.org/ti/
///