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

[James Whitehouse]

Tom,

Thanks, that's most helpful, I can limit my efforts to the thermo-switch on
the rad, and the 'resistor pack' you describe. I'd never come across that
resistor pack. I'll have to see if I can find it! I'll try looking
underneath the battery somewhere and have a poke around, as it sounds like
the symptoms you're describing are what I'm experiencing. Any idea what the
part no would be for that resistor pack?

Cheers,
James

> -----Original Message-----
> From: Tom Christiansen [mailto:tomchr at gmail.com]
> Sent: 29 August 2006 21:04
> To: James Whitehouse
> Cc: v6-12v at audifans.com
> Subject: Re: [V6-12v] Radiator Fans not switching in correctly...
> 
> James,
> 
> There are three thermosensors/switches in the system:
> 
> 1) Engine coolant temperature sensor (ECT) in the hard coolant line by
> the EGR valve. Port side, aft of engine. This is used by the ECU.
> 
> 2) Temperature sensor, switch on the starboard, aft side of engine by
> the ISV. This feeds the gauge on the instrument cluster as well as
> turns on the high-temp warning light.
> 
> 3) Thermoswitch in the bottom starboard corner of the radiator. This
> one controls the rad fans.
> 
> Even though I have A/C, my car (1994 90 S, AAH engine) only has one
> rad fan. The speed of it is controlled by the thermoswitch as well as
> a resistor pack mounted on the port side, forward subframe. More or
> less directly under the battery. If the resistor pack is fried, the
> fan will usually kick on at high-speed only. Resistors normally fail
> open so you'll get no fan action until the trip point for high-speed
> is reached. My rad fan turns on at low-speed when  I turn on the A/C.
> 
> Hope this helps.
> 
> Tom
> 
> On 8/28/06, James Whitehouse <james_whitehouse1 at yahoo.co.uk> wrote:
> > Guys,
> >
> > Anyone know the fault finding procedure for the radiator fans on this
> > engine? My engine manual doesn't cover this, for some reason (why?). I
> only
> > have fault finding for the ignition system, which covers the coolant
> temp
> > sender (G62), which feeds the Control Unit.
> >
> > However, I know that there are two other 'thermo switches', one being
> the
> > thermo switch that plugs in on the bottom left of the radiator housing
> > itself, and another (F76) which sits on the large coolant pipe on the
> left
> > rear of the engine (as you look at it from the front of the engine bay)
> > which I know feeds the dashboard temp gauge, but I believe may also have
> > something to do with the rad-fan timing, etc.
> >
> > There's also a relay or two in the fuse box and a couple of fuses, but I
> > don't have enough detail on what the two thermo-switches actually do to
> know
> > where to start.
> >
> > The symptoms are as follows:
> >
> > - 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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