Date: Sun, 28 Mar 1999 18:27:21 -0500
Reply-To: David Beierl <synergx@IBM.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <synergx@IBM.NET>
Subject: Re: Diagnosing cooling fan
In-Reply-To: <36FE9FDE.F9ECBF2F@mindspring.com>
Content-Type: text/plain; charset="us-ascii"
Ok, I've looked at the Bentley -- first of all, there's no mention of a
resistor pack in the schematics for any year that I looked at except
possibly the '83/84, where there's an ambiguous little symbol that could
possibly be a resistor. I've an '84 myself, maybe I'll look sometime. :)
Anyway, the current path for both low-speed and high-speed starts at fuse
S13, 30 amps. The low-speed power and relay power is supplied from
terminal C7 on the fuse block to a R/W 2.5mm to lug 3 of the thermoswitch.
There's a spade-terminal connector in this wire, somewhere under the dash.
Lug 2 of the thermoswitch feeds the low-speed winding by a 2.5 mm R/BK to
the motor harness. (Motor connector: 1 low 2 high - ground 2.5 mm BR).
That path is enough to diagnose a non-running fan, as the relay is used
only for high-speed. However, it is perfectly safe to short all three lugs
of the thermoswitch together, which will also activate the relay and the
second winding.
If you have a 12v test light, continue by testing terminal 3 of the
thermoswitch. It should have 12v at all times. If not, it's the fuse or
the wiring btw the fuse and the thermoswitch. With the thermoswitch
shorted, the motor (+) lead(s) should have 12v. If so, then hook the test
light to 12v and check the motor (-) lead. It should be grounded, so the
light should light again. This is actually the likeliest problem after the
fuse, as it is common to both motor windings. The motor ground goes back
to a multilug cluster behind the relay panel.
If you don't have a test light, they're fairly cheap and very useful, and
the fancier ones can pierce a wire's insulation. Otherwise you can use a
sewing needle or pin to test as needed. The needle is better as it makes a
smaller hole in the insulation. You can make a test light with any small
socketed 12v bulb, just run out a length of wire with a clip from one side,
and a short length with a point of some sort on the other side. A test
light is preferable to a voltmeter for this kind of tracing, as the light
puts enough load on the circuit to show some open circuits that a voltmeter
might pass as good under no-load conditions.
Any preguntas, just ask...
david
At 13:32 3/28/99 -0800, Rubatoguy wrote:
>Does anyone have a way to diagnose the radiator fan not coming on?
>(3-speed fan)
>
>I understand that it could be the relay, the thermoswitch or the
>resistor pack. I can't seem to find anythin in Bently as far as tracing
>the problem or even testing these components.
>
>Anyone know how to do it?
>
>
>
>Thanks
>Todd
>'88 Westy
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