You should be able to pull it out and check it with an ohmmeter.  The one
in our '91 failed some years ago due to corrosion if I recall correctly.
Fixed with careful disassembly and cleaning.

Larry A.

On Wed, Sep 2, 2015 at 2:54 PM, Jack Reynaert <jack007@comcast.net> wrote:

> Update:
>
> Changed the Tri-Pressure Switch, as by-passing resulted in unit running,
> but
> that didn't fix it
> Checked the resister behind head-light, working fine, as variable speed on
> Aux Fan working in high-heat.
>
> Ran a by-pass to the Aux-Fan, and able to charge and run the ac, when
> by-pass switch is on... so AC works with a manual switch.
>
> Could the issue be a bad A/C Fan Switch on our friend's 90 Westy?
>
> http://www.gowesty.com/ec_view_details.php?id=3314&category_id=69&category_p
> arent_id=
>
> Thanks!
>
> Jack
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Dennis Haynes
> Sent: Sunday, August 23, 2015 11:12 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Radiator Aux Cooling Fan 84 vs. 90 - compressor on for Aux Fan
> to kick-on with 90 model??
>
> In your case the compressor is out on a safety. As the controls are calling
> for the compressor the radiator fan is turned on.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> James
> Sent: Sunday, August 23, 2015 10:56 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Radiator Aux Cooling Fan 84 vs. 90 - compressor on for Aux Fan
> to kick-on with 90 model??
>
> In our '91, the radiator fan turns on when the AC is turned on, even
> without
> the compressor running (our compressor is in place, but the system has no
> charge, as the compressor needs replaced... the fan turns on anyway).
>
> James
> Ottawa, ON
>
> > Date: Sun, 23 Aug 2015 10:59:39 -0400
> > From: jack007@COMCAST.NET
> > Subject: Re: Radiator Aux Cooling Fan 84 vs. 90 - compressor on for
> > Aux
> Fan to kick-on with 90 model??
> > To: vanagon@GERRY.VANAGON.COM
> >
> > Once we get the AC charged, then I can test the low-speed fan with AC
> running.
> > BTW... Replaced Condenser, and both AC lines from Rear to Front (had
> > AC
> lines made up at local shop N. of Detroit for $225, with ends)
> >
> > Since the 1990 is much different than my 1984 Vanagon, it may require
> > the
> compressor running to turn on the low speed.
> > My 84 will kick the Aux fan on, just by turning on the AC (even at
> > higher
> temp, without the compressor running).
> > Does anyone know if the 1990 models require that the Compressor is
> > running
> for the Aux fan to kick-on?
> >
> > Note: we changed the temp sensor/switch on the Radiator and the fan
> > kicked
> on (low speed), when sitting at idle for a long while.
> > Glad I found my spare switch in my box of Vanagon parts :), didn't
> > realize
> I had one around, and the same switch is use on 84 / 90's.
> >
> > I really appreciate all the expert advice!
> >
> > Jack
> >
> > -----Original Message-----
> > From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> > Sent: Saturday, August 22, 2015 8:10 PM
> > To: 'Jack Reynaert'; vanagon@GERRY.VANAGON.COM
> > Subject: RE: Radiator Aux Cooling Fan 84 vs. 90
> >
> > I guess if it's on the Samba it must be true. The radiator fan switch
> senses the water temperature in the radiator closer the outlet than inlet.
> A
> higher temp thermostat will make less coolant flow until it fully opens
> allowing the radiator more time for it to cool. It is true that too low a
> temp fan switch will run the fan needlessly. A 75c switch is ridiculous. In
> hot weather with a good load you will never get the coolant temp that cool
> so the fan goes forever. If you use the AC the fan will run for the
> compressor anyway. If in this situation the radiator switch calls for the
> fan above that the radiator is either saturated with heat due to extreme
> conditions including it may not be good or the fan switch is too low.
> >
> > Dennis
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> > Behalf Of
> Jack Reynaert
> > Sent: Saturday, August 22, 2015 7:57 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Radiator Aux Cooling Fan 84 vs. 90
> >
> > Dennis and everyone else,
> >
> > Thank you for your great information.
> >
> > PS... was thinking about the low-temp switch, but just saw this on
> TheSamba.
> > "Just remember that the fan switch needs to be matched with the
> thermostat. If you run the low temperature fan switch with a higher than
> stock thermostat the fan may well run too often."
> >
> >
> > Jack
> >
> > -----Original Message-----
> > From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
> > Sent: Saturday, August 22, 2015 4:31 PM
> > To: 'Jack Reynaert'; vanagon@GERRY.VANAGON.COM
> > Subject: RE: Radiator Aux Cooling Fan 84 vs. 90
> >
> > The wiring and operation of the 90 is drastically different than in
> > the
> 84. The fan motor is much larger, one speed using a resistor to provide
> lower speeds and multiple relays for control. Also depending on variations
> some will have the cooling fan low speed operation effected or even
> disabled
> if the AC wiring is hacked. Here is a brief summary of expected operation.
> >
> > Engine cooling
> > When radiator fan switch calls for low speed cooling the switch
> > directly
> supplies power from the fuse block through the resistor to the motor.
> > When same switch calls for high speed there is a relay above the fuse
> box.
> This relay brings power directly from the battery (own wire) through a
> fusible link directly to the fan motor. A failed fuse for the control and
> low speed disables both these systems.
> >
> > To support the Air conditioner
> > When the compressor is on the fan runs at a low speed energized from a
> relay in the AC system. This also depends on the fan resistor.
> > If system (AC) high side pressure increases due to insufficient
> > cooling a
> pressure switch operates a relay in the fuse box to increase the radiator
> fan speed. Basically the other side of the fan resistor is placed in
> parallel increasing current flow and thus fan speed.
> > If pressure continues to climb at some point the AC will get cut out
> > and
> the fan will still run at the higher speed until it drops.
> >
> > There are number of different pressure switch set ups. Most of the
> > late
> vans use a single switch with multiple function often known as a trinary
> switch.
> >
> > Trinary switch functions
> > Low pressure (lost charge) cut out.
> > 2 speed condenser (radiator) fan.
> > High pressure cut out.
> >
> > The 84 has none of these features or safeties. They just self-destruct
> when things go wrong.
> >
> > Dennis
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> > Behalf Of
> Jack Reynaert
> > Sent: Saturday, August 22, 2015 2:25 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Radiator Aux Cooling Fan 84 vs. 90
> >
> > When I run the AC on my 84 Westy, the Aux. fan on the Radiator runs as
> long as the power is on to the AC in back (regardless if the compressor is
> on).
> > When I'm stuck in traffic, and the temp gage rises, the Aux fan does
> > not
> kick-on by itself.  So, I turn on the AC, without compressor, and the fan
> kick's on and the temp gage goes down.  I suspect the temp sensor on the
> radiator is bad, and plan to change it.
> >
> > Now, my question is related to the Aux radiator fan on the 90 Westy we
> > are
> just about complete with the mechanical overhaul (including new 2.2 GW
> motor, brake system, radiator, condenser, LED upgrades, dash rebuilt with
> AWESOME GW Kit, new everything that attaches to the GW motor as well).
> >
> > We took it for a ride today, and even at full operating temperature,
> > the
> aux fan didn't kick on.  Put 12v to the fan motor and it worked fine, fuse
> #1 fine, power to the red/white wire to the switch etc.  However, when we
> turned on the AC, the aux fan didn't turn on (like it does on my 84)... is
> that normal for a 90?
> >
> > Any suggestions on likely causes (relay #53 or temp. sensor lower
> > drivers
> side of radiator?)
> >
> > Thanks for any insight!
> >
> > Jack R.
> > N. of Detroit
>