Date:         Sun, 25 Apr 2010 11:36:30 -0700
Reply-To:     mark drillock <mdrillock@COX.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         mark drillock <mdrillock@COX.NET>
Subject:      Re: Water Cooler System Design Flaw Workaround?
In-Reply-To:  <y2k71d9cdf91004251022r2e8ed7a7lcfca98e87661bfca@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I have fooled around more than most with Vanagon radiator fans, temp
switches, manual over-ride switches, etc. I'd say the best thing is to
start with a new radiator, new 2.1 spec radiator fan temp switch, and
FIX the weak spots in the fan power wiring. Then there will be no need
for a manual switch.

82-85 have real weaknesses in the rad fan wiring as well as only the
smaller fan and generally older radiators.

86+ tend to be ok other than the ground for the fan and burned out low
speed on the fan resistor for a/c models. If you have one with the 450
watt fan you should have little use for a manual switch unless you tow
in mountains in summer. Otherwise something is wrong and the manual fan
switch is helping you avoid fixing it.

82-85 can get a major improvement in fan performance by installing a
separate power path from the battery to the fan wiring and eliminating
all fan circuit connections to the main fuse box along with putting a
ring terminal on the ground wire. The fuse box and wiring was under
designed for heavy rad fan use.

I have measured start-up current on the later 450 watt fan and have
briefly seen as high as 110 amps when wired directly. That is why VW ran
a separate additional power wire right from the battery to the fan high
speed relay for those models. The silly spade connector ground is a
common failure point in big fan models and can be intermittent until you
really need it when it craps out entirely.

If you must install a manual switch the best way is to use it to control
the stock high speed relay. That way almost no current need flow through
your added switch and wires.

Mark


Jake de Villiers wrote:
> Hey David, a manual fan switch makes sense for the West. I really wished for
> one on a trip from here to Wyoming in 103 degree temperatures.
>
> When approaching the long (15 - 30 minute) second and third gear grades
> through Eastern Washington and Idaho you'd turn on the fan before the rad
> got too hot.
>
> Seems to me if you were pulling more air through the core the coolant
> temperature would stay lower overall.
>