[928uk] S4 Overheating - Temp Sensor Operation

[jon928se at gmail.com]

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
>     >>>
>     >>>
>