[928uk] S4 Overheating - Temp Sensor Operation

[Ben Hodges]

Hi Jon - I think that’s a temp switch? The pressure switch is there to stop
the compressor clutch kicking if there’s no gas/pressure in the system.

On Wed, 5 Jun 2024 at 13:05, Jon Holdsworth via 928uk <
928uk at lists.928.org.uk> wrote:

> Short circuit the pressure switch on the top of the receiver dryer
> canister and the fans will come on MAX when the AC button is pressed in.
> This seems to be irrespective of internal or external air temperature.
>
> Jon in Sydney
>
> -----Original Message-----
> From: 928uk <928uk-bounces at lists.928.org.uk> On Behalf Of Paul R Smith
> via 928uk
> Sent: 05 June 2024 21:34
> To: Paul <ukkid35 at gmail.com>
> Cc: 928uk at lists.928.org.uk
> Subject: Re: [928uk] S4 Overheating - Temp Sensor Operation
>
> I have never noticed fans coming on with a cold engine just because the
> A/C is switched on. Does yours do that now?
> (I can't check on my GT now as it currently has zero A/C pressure).
>
> Smiffy
>
> On 05/06/2024 11:58, Paul wrote:
> > Here's the section that mentions using the aircon to force the fans on:
> >
> > *TROUBLESHOOTING THE COOLING FANS (‘87 AND UP CARS)*
> >
> > Turn the ignition switch on, but don’t crank the engine. Turn the A/C
> > on, with the blower on speed 2. Both cooling fans should run at low
> speed.
> >
> >
> > I had a problem yesterday, thankfully resolved now - I don't have the
> > original plugs on the ends of the fan leads which fooled me into
> > thinking I'd connected the cables when in fact I hadn't
> >
> >
> > I used the email from earlier because it had some useful info at the
> > beginning, I didn't notice that it had been truncated
> >
> >
> > Paul
> >
> > 87 S4 Manual
> >
> >
> > On Wed, 5 Jun 2024 at 09:54, Paul R Smith via 928uk
> > <928uk at lists.928.org.uk> wrote:
> >
> >     That's a big document, and I can't see what you refer to.
> >     But I'm a bit confused, the email you are replying to is from
> >     2007. Do
> >     you have a current problem, or are you pre-emptively checking your
> >     fan
> >     system?
> >
> >     Smiffy
> >
> >     On 05/06/2024 08:17, Paul via 928uk wrote:
> >     > For anyone who needs an easy to read diagnostic guide, this is
> >     invaluable
> >     >
> >     > https://www.928gt.com/T-WallyHVAC.aspx
> >     >
> >     > However, the method he advises to force the fans to run does not
> >     work on my
> >     > car, probably because my aircon has lost pressure and is not
> >     operational at
> >     > the moment
> >     >
> >     > Therefore I made this by taking an old temp sensor, breaking off
> >     the brass
> >     > section, and twisting the wires together
> >     >
> >     > Then I removed the connector to the radiator temp switch and
> >     plugged it in
> >     > there, this forces the fans to run with the ignition on
> >     >
> >     > https://thumbsnap.com/i/JCzAYETX.jpg
> >     >
> >     > Paul
> >     > 87 S4 Manual
> >     >
> >     > On Mon, 21 May 2007 at 11:45, Paul<ukkid35 at gmail.com> wrote:
> >     >
> >     >> Quote from EuroCarParts for:
> >     >>
> >     >> Rad Sensor (Fan Switch)
> >     >> Temp Sensor (I or II - not known)
> >     >> Thermostat
> >     >>
> >     >> £90, but at least they are all in stock. I won't know which temp
> >     >> sensor they have, Temp I or Temp II, until I see it though.
> >     >>
> >     >> Not exactly a bargain, but it's no fun when they're faulty.
> >     >>
> >     >> Paul
> >     >> 87 S4 Manual
> >     >>
> >     >> On 20/05/07, Paul<ukkid35 at gmail.com> wrote:
> >     >>> No sign of it escaping from the overflow hose, but I hope
> >     that's where
> >     >> it's
> >     >>> going - where else could it go?
> >     >>>
> >     >>> Switching the aircon on seems to keep the temp under control,
> >     but there
> >     >> was
> >     >>> an initial very high reading after about 4 mins driving, which
> >     then
> >     >> dropped
> >     >>> to normal, I'm guessing was when the thermostat opened -
> >     perhaps there
> >     >> was
> >     >>> an air lock.
> >     >>>
> >     >>> I'm tempted to replace Temp I, Temp II, the Rad sensor and the
> >     Thermostat
> >     >>> all at once. In the past I would have been more frugal, but
> >     for once I
> >     >> can
> >     >>> aford to be a bit more extravagant.
> >     >>>
> >     >>> Paul
> >     >>> 87 S4 Manual
> >     >>>
> >     >>>
> >
>
>