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

Wed Aug 30 01:11:11 EDT 2006

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?
> > >>>
> > >>> TIA
> > >>>
> > >>> James
> > >>
> > >> --
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> > >>
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> > >
> > >
> > >
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