[Vwdiesel] 85 Jetta turbo diesel auxiliary radiator fan mysteries

[W Davis]

1985 Jetta GL 1.6L turbo:

It has benn very hot here in Fla, and I have noticed
problems with the aux radiator cooling fan.

I firgure the fan is not working properly, because in
stop-and-go traffic (idling in hot weather), 
the temp indicator shows the
engine is running hottter than norma. 

In clear traffic, driving at cruising speed, temp
needle will come down to a normal level.

I can let the engine idle in my driveway, watch the
fan start up, and I can wiggle the 3-pin plug powering
the fan, and the fan will behave erratically, so I believe
the problem is either the connector on the fan itself, or 
the female connector that plugs into it.

There are plenty fans avaiable for replacement, new and used...
..but I seen none avaialbe with the following:

...the fan in my car has an additional connecton coming out from
the rear of the fan motor..it appears to be just a hose, and just goes dowm towards the bottom of the radiator, and has an open end.

That is mystery # 1.

Mystery #2 is that there are only 3 blades on this fan assembly.

I see no aftermarket, or used MK2 fan assemblies for sale with 3 blades,
just the normal looking 5 blades.

The fan motor has a hard-to-read label, with the VW mark, 
a (brand?) name something like "Nahenstlot"
with an umlaut over the "O", and a number
that does not show up in VW parts number searches.

431 959 455 L

SO, friends...

What is that hose coming out of the rear of my fan motor,
and, is it odd that I have a fan with only 3 blades?

Mny thanks in advance for any clues,

Bill Davis
Clearwater FL
1985 Jetta GL 1.6L turbo diesel running great,
except for this.