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

Sun Sep 3 09:05:26 EDT 2006

Poncho,

It's not running correctly, it's switching in too late and then not staying
on long enough to actually cool the engine. If the car is stationary, the
temps will gradually rise up and up.

The biggest indication is that it's not running as it used to. You would get
the fans kicking in at first stage half way between the centre mark and the
next mark up. These would usually bring the car back to 'centre'/ normal
temp. Only in extremely hot weather in traffic would the second stage kick
in, which would bring the temp back down to the first stage. Now the car
just waits til the second stage kicks straight in, only stays on for 20
seconds, then goes off without really cooling anything at all.

James

> -----Original Message-----
> From: Poncho [mailto:ponchojuan66 at yahoo.com]
> Sent: 02 September 2006 02:41
> To: Tom Christiansen; James Whitehouse
> Cc: v6-12v at audifans.com
> Subject: Re: [V6-12v] Radiator Fans not switching in correctly...
> 
> 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)...
> > > > >>
> > > > >> Now, having said that, are you SURE the
> > radiator is getting the hot
> > > > >> fluids in volume? A partially-blocked or
> > slow-opening/inop thermostat
> > > > >> valve at the block might be preventing the
> > radiator from getting the
> > > > >> hot fluids in volume, and thus the sensors
> > for the radiator aren't
> > > > >> reading it as too hot (just a thought).
> > Taking a kitchen probe or
> > > > >> laser/infra-red temp probe to the radiator
> > and hoses should tell you
> > > > >> definitively (a hand would probably tell you
> > too, but I won't suggest
> > > > >> you potentially burn yourself to find out).
> > > > >>
> > > > >> Good Luck!
> > > > >> =-= Marc Glasgow
> > > > >>
> > > > >> On Aug 28, 2006, at 6:36 AM, James Whitehouse
> > wrote:
> > > > >>>
> > > > >>> - Engine waits until it's one mark beyond
> > the 'normal' temp mark
> > > > >>> (the more
> > > > >>> distinctive 'centre' thicker splodge of
> > white mark on the dash),
> > > > >>> then both
> > > > >>> fans kick in (full speed?) for about 20
> > seconds. They then turn off
> > > > >>> again
> > > > >>> without having cooled the engine.
> > > > >>>
> > > > >>> I'm guessing that a) first speed fans aren't
> > working, as I remember
> > > > >>> them
> > > > >>> kicking in before that mark, and staying on
> > longer, then 'speed 2'
> > > > >>> kicking
> > > > >>> in when sitting in traffic for ages,
> > bringing it down to 'speed 1'
> > > > >>> temp.
> > > > >>>
> > > > >>> If anyone has info, or fault finding for
> > this system, could you let
> > > > >>> me know
> > > > >>> please?
> > > > >>>
> >
> === message truncated ===
> 
> 
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