[928uk] S4 Overheating - Temp Sensor Operation

[Ben Hodges]

Ahh - applying my early car logic to later cars again. Slaps wrist.

Thanks Smiffy

On Wed, 5 Jun 2024 at 13:58, Paul R Smith <smiffypr at gmail.com> wrote:

> No, S4 uses high refrigerant pressure to indicate need for fan.
> S uses high refrigerant temperature.
>
> All need a minimum pressure before they run the compressor.
>
> Smiffy
>
> On 05/06/2024 13:30, Ben Hodges wrote:
>
> 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
>> >     >>>
>> >     >>>
>> >
>>
>>
>