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

Wed Aug 30 15:12:44 EDT 2006

Tom, Marc,

Thanks for that info. My car doesn't have an external temp sensor - I think
it's a slightly older (1992) generation before the digital dash? At least it
doesn't the (then optional?) onboard computer...

Cheers,
James

> -----Original Message-----
> From: Tom Christiansen [mailto:tomchr at gmail.com]
> Sent: 30 August 2006 06:11
> To: James Whitehouse
> Cc: The CyberPoet; v6-12v at audifans.com
> Subject: Re: [V6-12v] Radiator Fans not switching in correctly...
> 
> 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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