Date: Thu, 1 Apr 2010 23:17:47 -0700
Reply-To: Alistair Bell <albell@SHAW.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@SHAW.CA>
Subject: rad fan won't turn off troubleshooting story
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
I just posted this tale of woe and finally victory tracking down a
rad fan that would not turn off. pics and wiring diagrams to
accompany this stirrign tale can be found here;
Local friend and '91 syncro Westfalia owner called me last weekend
for some help in tracking down an unusual problem. I'll list the
symptoms in point form:
- he had been away for a couple of weeks and the van was parked.
- when he came back the battery was dead.
- his wife noted that the van was making "ticking noises".
- when he used booster pack to start van, the radiator fan came on
and was making a "twig caught in the blades" noise.
- the fan would come on with ignition on.
His first thought was bad radiator temp sensor, so he disconnected it
(lower right part of radiator, as you face the van). Even
disconnected the fan would come on when ignition on.
I came over at that point and we first dropped the spare tire to look
up at what the rad. fan was hitting to make such a noise. Turned out
that the 15" wheels and beefy tired spare had pushed up a section of
black plastic tubing (which I am guessing is the brake vacuum line)
so that the fan blades would hit it. It wasn't worn away enough to
make a hole, but it was close.
We then started to pull fuses to see why the fan would come on even
with thermo switch pulled. Oh, I have to say at this point the van
does not have, nor ever did have, air conditioning (a/c complicates
rad fan control a bit). We were using the Bentley manual, following
the wiring diagram for a 91 westy. If it was all according to Hoyle,
pulling fuse #1 should have removed power from both speed stages.
We were puzzled for a bit, thing did not make sense. Also we noted
the rad fan had 2 red wires leading to it where above diagram shows
red and red/black.
Clearly we were on the wrong track.
We looked through Bentley and found a wiring diagram for a 450 W rad
fan (in 1986 model tear section).
We found the relay and 50 A fusible link above and to the left of the
fuse panel, right above the grounding "crowns". Remember, still at
this time, the rad fan would come on if ignition turned on, even if
fuse #1 is pulled and thermoswitch disconnected. Oh and also the
wiring diagram shows a blue wire into the thermoswitch where the van
had a red/blue wire.
We pulled the relay and lo and behold the fan would not come on, yah!
Funny thing was, the relay checked out ok using multimeter and it
clicked on and off when energised. Putting the relay back in made tha
fan come on, but this time disconnecting the thermoswitch turned the
fan off.
So we bought a new thermoswitch and swapped it in (this is not the
time to tell what we found in the rad when we pulled old switch out)
and everything worked as it should.
Theory time: we figure that when the van was sitting, the
thermoswitch failed and allowed the second stage fan speed to come
on. The brake booster vacuum line was worn and the battery drained.
My friend's wife must have heard it at the end of the battery life
when the fan was slowly turning and making a clicking noise as it hit
the brake booster vacuum line. This long run time caused the second
stage relay to stick in the on position. Pulling the relay, the
jiggling etc, caused the relay to open, and was then "under the
control" of the thermoswitch, and again fuse #1.
It was a learning experience :)
alistair
'86 syncro 7 passenger
'82 westy, diesel converted to gas in '94
http://www.members.shaw.ca/albell/
http://shufti.wordpress.com
