At 04:00 PM 2/10/2013, neil n wrote:
>I installed an '85 rad fan, wiring, etc. into my '81 so you'd think I
>would know this but .....
>
>In Bentley, I see that the diesel and Digijet fan motor have a low
>speed resistor. The 2.1 fan only shows connections at motor.
>
>Do both 2 speed fans have an internal resistor for the lower speed or
>does the 2.1 use different size coil windings to achieve the different
>speeds?

So far as I know there are only two fans for all watercooled; a
250-watt two-speed fan and a 450-watt single-speed fan with speeds
controlled by an external resistor pack.  It's been my impression
that the two-speed fan has high and low-speed windings, but I don't
know for certain.  The 450-W fan is listed by VW for use in high-temp
(desert?) areas and trailer towing IIRC, and it is the one installed
in all A/C US Vanagons.  If changing from one fan type to the other,
you also have to change the fan shroud (as well as the wiring of
course).  For ordinary engine cooling each fan has two functional
speeds, normal and high (or normal and take-off power in the case of
the big one).  My recollection from long-ago reading of the A/C
diagrams is that the A/C operation introduces a third intermediate speed.

The radiator temp switch controls the low speed directly and the high
speed via a relay for both sizes of fan.

Yours,
David