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

James Whitehouse james_whitehouse1 at yahoo.co.uk
Tue Aug 29 13:13:34 EDT 2006


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.


> -----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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