Hello from 90 degree NYC:

Why does the Bentley wiring diagram for an 87 show two positive posts
on the radiator fan motor, when my fan motor has just one positive
post and one negative post? Both hot leads are combined in one
connection at the positive post on my motor, 251959455M. My vanagon
has A/C.

How does the fan motor know whether to go high speed or low speed? My
low speed option isn't working and i'd like to fix it.

I get 12.1 volts on the low speed lead and 12.6 volts on the high
speed lead  when I jump the radiator thermoswitch (red/black wire and
red/blue wire, respectively). If the single positive post is correct,
does this mean I need a new fan motor? Or should the low-speed voltage
be higher than 12.1? High-speed works fine: the relay clicks and the
fan spins very nicely.

I've searched the archives and apparently there was something about
this on Ken Wilford's site at one time which I can't find.
-- 
Garrick, Queens, NY
'87 GL Weekender

*****
With fond remembrances of:
'77 Beetle 
'67 Bus 
'59 Pickup sn# 460440
'67 Beetle
'76 Camper Bus