[V6-12v] Radiator Fans not switching in correctly...

Sun Sep 3 09:07:50 EDT 2006

A good thought, but if this were the cause, would both fans work at the 2nd
stage/ full speed?

James

> -----Original Message-----
> From: Wilfried Link [mailto:wilfriedlink at yahoo.com]
> Sent: 03 September 2006 05:46
> To: Poncho; Tom Christiansen; James Whitehouse
> Cc: v6-12v at audifans.com
> Subject: Re: [V6-12v] Radiator Fans not switching in correctly...
> 
> I had similar problems with my 95 A6. Turned out all
> switches and relays were fine. The cause was one of
> the electric cooling fans was worn out -- the carbon
> brushes on the motor just plain too short to
> consistently make it run. After replacing it,
> everything worked fine again. About a year later, the
> other fan motor stopped working as well. Replace it,
> all is well again. The car had about 190,000 miles on
> it. If you can find a shop that will replace the
> brushes, consider that option -- the brush contact
> area was too worn on mine, but the new fans vibrate
> noticeably when compared to the silky smooth original
> ones.
> 
> Wil
> 95 A6 Avant
> 
> --- Poncho <ponchojuan66 at yahoo.com> wrote:
> 
> > SOunds like its running correctly.  The sensor on
> > the
> > raditor is actually a switch to control the fan (
> > through the resistor block).  This is configured
> > differently on depending on number of issues.
> >
> > Normally the fan will come on when the temp guage
> > reaches just ubove top dea center on the guage.  It
> > will typicallu stay on for a fe mimutes and shut
> > off.
> > You will not notice much movement in the guage.  The
> > reason is the water is cooled in the radiator and
> > the
> > guage "sensor" is the one on the heater hose behind
> > the engine.
> >
> > The whole thing is working IF the you keep the car
> > idling and it stays around the middel of the guage.
> >
> > Under way ( 30MPH or more) , it should eventually
> > return to the 1/3 mark.  IF you don't trust it, you
> > can check the temp witha a meter a temp probe.  But
> > I
> > would not worry too much.  Aslo make sure you are
> > running the right mix of antifreeze and the
> > expansion
> > cap is ok.
> >
> > poncho
> >
> > --- Tom Christiansen <tomchr at gmail.com> wrote:
> >
> > > Marc, James:
> > >
> > > The external thermometer is a completely different
> > > circuit. The sensor
> > > is located behind the lower grille by the port
> > side
> > > foglight. It's a
> > > NTC resistor. It's resistance at ~70F/20C is
> > roughly
> > > 1500 ohm (easily
> > > verified with an ohmmeter). It has a 2-pin
> > connector
> > > that's wire-tied
> > > to the bottom of the battery 'shelf'. From there,
> > > the wires go via the
> > > fat wiring harness into the instrument cluster,
> > > where it ends up as
> > > pin 2 in the connector for the thermometer
> > display.
> > > It's the brown
> > > wire with a yellow stripe. Measure the resistance
> > > from that
> > > yellow/brown wire to ground and you should get
> > 1500
> > > ohm at 20C/70F.
> > >
> > > The reason I know is that that wire got pinched to
> > > ground when I
> > > replaced the heater core. I recently ran another
> > > wire to get the
> > > display to work. It was showing 'E' all the time.
> > > Drove me nuts...
> > >
> > > Aside from the 'E' in the display I noticed no
> > > ill-effects of having
> > > that wiring messed up.
> > >
> > > Tom
> > >
> > > On 8/29/06, James Whitehouse
> > > <james_whitehouse1 at yahoo.co.uk> wrote:
> > > > Marc,
> > > >
> > > > It's a valid question, but I don't know what
> > > sensor reads the outside temp -
> > > > which one are you thinking of, and how would I
> > > check whether it's accurate?
> > > >
> > > > Thanks for the zinc paste info!
> > > >
> > > > Cheers,
> > > > James
> > > >
> > > > > -----Original Message-----
> > > > > From: The CyberPoet
> > > [mailto:thecyberpoet at cyberpoet.net]
> > > > > Sent: 29 August 2006 20:42
> > > > > To: James Whitehouse
> > > > > Subject: Re: [V6-12v] Radiator Fans not
> > > switching in correctly...
> > > > >
> > > > > here's some more info on those zinc-suspension
> > > pastes:
> > > > > http://sw-em.com/anti_corrosive_paste.htm
> > > > >
> > > > > Q: are you getting a valid reading from the
> > > outside temp sensor? If
> > > > > it's reading way too low or not at all, it
> > might
> > > affect the system
> > > > > logic for the fans...
> > > > >
> > > > > Cheers
> > > > > =-= Marc
> > > > >
> > > > > On Aug 29, 2006, at 1:13 PM, James Whitehouse
> > > wrote:
> > > > >
> > > > > > Marc,
> > > > > >
> > > > > > Thanks for that, I'll try cleaning the
> > > connector on the radiator-
> > > > > > mounted
> > > > > > thermo switch first. I don't have any
> > > knowledge of anything similar to
> > > > > > 'Nolox', but I use DeoxIt as a contact
> > cleaner
> > > often and it seems
> > > > > > to work
> > > > > > OK. If that doesn't help, I'll probably try
> > > replacing that thermo-
> > > > > > switch
> > > > > > first, followed by the 'radiator fan 1st
> > > speed' relay in the fuse
> > > > > > box -
> > > > > > they're not expensive parts.
> > > > > >
> > > > > > If anyone else has any more info/ specs on
> > the
> > > system, please let
> > > > > > me know,
> > > > > > I'd be grateful for any fault finding
> > > procedures, etc.
> > > > > >
> > > > > > Cheers,
> > > > > > James
> > > > > >
> > > > > >
> > > > > >> -----Original Message-----
> > > > > >> From: The CyberPoet
> > > [mailto:thecyberpoet at cyberpoet.net]
> > > > > >> Sent: 28 August 2006 12:22
> > > > > >> To: James Whitehouse
> > > > > >> Cc: v6-12v at audifans.com
> > > > > >> Subject: Re: [V6-12v] Radiator Fans not
> > > switching in correctly...
> > > > > >>
> > > > > >> This isn't my area of expertise, but I do
> > > know that on my V6's (at
> > > > > >> least based on my experiences), the
> > following
> > > seems generally true:
> > > > > >>
> > > > > >> (A) There are two electrically-driven fans,
> > > the primary one triggers
> > > > > >> on temp of the radiator temp sensor, and
> > the
> > > second of which triggers
> > > > > >> based on air conditioning use (as well as
> > > kicking on at a higher
> > > > > >> thermal level threshold for the
> > > radiator/engine).
> > > > > >>
> > > > > >> (B) The wiring connectors for the sensors
> > is
> > > often the first thing to
> > > > > >> go bad, because of exposure in my
> > experience.
> > > Cleaning the contacts
> > > > > >> thoroughly & dielectric grease is often the
> > > best place to start.
> > > > > >> Sidenote: I've found a dielectric grease
> > > called Nolox that contains
> > > > > >> zinc particles in the suspension which
> > forces
> > > a fresh cut through
> > > > > >> surface corrosion on connectors every time
> > > the plugs are mated works
> > > > > >> better than traditional vasoline-like
> > > dielectric grease if there is
> > > > > >> already a problem with connectivity. There
> > > are Brit-market
> > > > > >> equivalents (I selected Nolox because all
> > the
> > > other options were UK-
> > > > > >> based and not readily available here). This
> > > is not a total solution
> > > > > >> for bad connectivity, but given a connector
> > > that already had to be
> > > > > >> cleaned of surface corrosion once, I'll
> > grab
> > > the nolox just to
> > > > > >> improve the situation in the future (such
> > as
> > > plugging/unplugging tail
> > > > > >> light connectors on the road where I don't
> > > carry a full toolkit with
> > > > > >> sandpaper, etc. with me)...
> > > > > >>
> >
> === message truncated ===
> 
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