Your Syncro already has the "third" fan speed and the relay for it. What
you are missing is the second speed with it's relay and wiring. The
diagrams can be confusing about this since the 2 speed version calls
full speed the 2nd speed and the 3 speed version calls full speed the
3rd speed.

Assuming that you pulled the complete fan wiring sub-harness from your
86+ A/C donor it should be straight forward to remove the lo/hi version
fan wiring and install the low/med/hi wiring in it's place. VW made this
area of the wiring flexible by design so they could use any of 3 fan
wiring schemes without needing different main harnesses. It is plug and
play.

You need to unplug the Syncro fan harness illustrated on Bentley 97.200
and replace it with the A/C fan harness illustrated on 97.141. Dash out
will be helpful. No wires need be cut. Everything unplugs.

Mark

Joe Federici wrote:

> Does anyone on the list have experience adding the factory AC wiring
> to a non-AC van. The only part I'm interested in is the 3rd speed
> radiator condenser fan and which wire triggers it.
>
> I'm going to be using a different condenser and evaporator and just
> need to wire in the needed relays or wiring to activate the fan and
> wire it into my system so it comes on with the compressor. I've got
> all the wiring and relays from a parts van that had AC but I'm having
> trouble figuring out what I need and don't need. My van is a 1987
> syncro transporter so I've already got the fan used for the AC vans.
> Looking at the manual I think all I need is to add the 2nd and 3rd
> stage fan relays. One looks to be above the fuse panel and other is
> behind the left fresh air vent but I'm not sure about the trigger
> wire that activated the 3rd speed.
>
> If any knows please pmail me,
>
> thanks
>
> JFF
>