Xantia HDi STOP Light

[DickieG]

One thought about some S2 cars apparently doing it and not others is it could be a fault with the contacts in the air direction slider... I notice that sometimes I don't get the fan speed boost when I switch to demist while other times I do (in fact the auto fan setting has a bit of a mind of its own...) so if that's the switch contacts being a bit dodgy that might also affect any auto A/C function...

Logical explanation there Simon.

[Bannedbiker]

My 1999 S2 1.9Td doesn't do it.

I seem to remember reading somewhere that there was a revision about 2000 where the air-con came on with de-mist where it didn't before.

Could have been in them manuals I sold you Roger (have you managed to read them fully yet?)

Martin.

[citroenxm]

No, I defenatly cannot agree on the XM there Jim..

My V6 SEi never did............................ Oh wait a min... Im talking to myself


Forget it... Im not gonna waste my time..

Nice one Jim, Arent you lucky there................

[CitroJim]

Oh wait a min... Im talking to myself

No you're not Paul

All I know is when I press the demist button on the XM, the aircon light illuminates and the cooling fans come on...

And I'm not denying at all that some S2 Xantias don't spark up the aircon on demist... There's plenty of evidence for that...

It's just all the S2s I've had do...

[citroenxm]

You have the factory Air Con in yours with the electronic panel...

Thats right, they do, BUT the difference there Jim, is the panel actually Physically Switch's the Air Con on itself. In the Xantia, the button doesn't switch obviously..so theres no way of telling if the Air Con is on unless you hear the cooling fans run or not. So, YES. IM WRONG AGAIN... YaaY Wrong again... Think I may take a year out, and sort myself out... Its not good telling people the wrong things.

Im gonna have a good year in 2013.. with any luck, might start talking decent things instead of crap, and with any luck start driving an XM again...

[CitroJim]

Im gonna have a good year in 2013.. with any luck, might start talking decent things instead of crap, and with any luck start driving an XM again...

Paul, you never talk crap - ever. End of. And don't you dare take a year out... This forum and club-xm can't do without you!

Here's to you having a great 2013 and getting an XM back where it belongs - on the road

[andy5]

My 99 Xantia HDI runs the air conditioning without it being switched on. Sometimes people point out on the ground what they think is a fluid leak by the left wheel arch, but it's just condensation dripping off the heat exchanger.

But more in line with th question - I think it is most likely just the level.

My front fans sometimes don't work on the first speed as the thermo switch needs sorting out, and there may be a flashing light if the thing definitely is too hot and just before the second speed starts in a traffic jam.

The first time I ever saw the flashing light I was towing a trailer up Birdlip hill on a warm summer evening. I slowed down and it went off, then I stopped for a few minutes at the top, but couldn't find any problem. Now I suspect this was when the thermo switch for the radiator fan speed first started to play up, since when it has been changed or cleaned a number of times (and it's due again)

But if it's not too hot then perhaps there is a slight coolant leak around the neck of the expansion tank or where the level indicator switch is plugged in. Mine flashes like that sometimes and also does slowly lose fluid for a while and then stabilise. Sometimes when it flashes a slight acceleration and thus presumably slight warming and expansion will turn the flashing off again. That's why I suspect the leak might be almost level with or at the level indicator. I must have a look around or get someone who knows the cars better to do so ...

[Mandrake]

Steady on guys, I wasn't intending to start a bun fight in here...

Considering how unreliable electronics in Citroens are I can quite believe that some do work and some don't... and we know that there are at least two versions of the climate control A/C which changed over around the S1 to S2 transition...

I certainly notice the behaviour of the climate ECU in my S2 is very different to my S1, for example the S1 auto fan comes on at full blast in cold conditions before the heater has warmed up whereas the S2 sensibly keeps the fan very slow if the ambient temp is low and the heater has not yet warmed up, gradually increasing it when the heater core does warm up...

Maybe the auto A/C in demist mode only activates under certain combinations of inside and outside temperatures as well. Who knows... Relax everyone.

[Rhothgar]

All become a bit convoluted!

Anyway, thanks for asking guys. I'm fine. Made it back alive and in one piece.

I didn't want to top it up whilst it was hot and it was blowing a gale yesterday morning. I poured a litre of water in the direction of the header tank. I suspect about half litre actually found its way into header tank.

Light was off so possibly just a glitch.

I'll keep an eye on it. It was at the bottom of the insert before filling.

[CitroJim]

Good news Roger

All become a bit convoluted!

It's the FCF Would you expect any less

[citroenxm]

Steady on guys, I wasn't intending to start a bun fight in here...

Considering how unreliable electronics in Citroëns are I can quite believe that some do work and some don't... and we know that there are at least two versions of the climate control A/C which changed over around the S1 to S2 transition...

I certainly notice the behaviour of the climate ECU in my S2 is very different to my S1, for example the S1 auto fan comes on at full blast in cold conditions before the heater has warmed up whereas the S2 sensibly keeps the fan very slow if the ambient temp is low and the heater has not yet warmed up, gradually increasing it when the heater core does warm up...

Maybe the auto A/C in demist mode only activates under certain combinations of inside and outside temperatures as well. Who knows... Relax everyone.

Way HEY.. allas, something else mine does NOT do! On auto if the slider temp is set to low or to high to the cars sensored temp then low and behold we have a gale blowing... So if the car water temp is cold.. we have cold air blowing... etc.. So really, the whole Climate control stuff IS crap.. I also find the Auto setting doesn't work.. It will blow HOT, then stay hot to about 20deg then go straight to cold!! It doesnt regulate the temp at all...

[MTND]

the click from the compressor clutch was quite obvious on that car...

The only "click" I get on mine is the normal "Citroen" click and that not very much!

Sorry had to comment on clicks as I haven't got aircon

[Mandrake]

Steady on guys, I wasn't intending to start a bun fight in here...

Considering how unreliable electronics in Citroëns are I can quite believe that some do work and some don't... and we know that there are at least two versions of the climate control A/C which changed over around the S1 to S2 transition...

I certainly notice the behaviour of the climate ECU in my S2 is very different to my S1, for example the S1 auto fan comes on at full blast in cold conditions before the heater has warmed up whereas the S2 sensibly keeps the fan very slow if the ambient temp is low and the heater has not yet warmed up, gradually increasing it when the heater core does warm up...

Maybe the auto A/C in demist mode only activates under certain combinations of inside and outside temperatures as well. Who knows... Relax everyone.

Way HEY.. allas, something else mine does NOT do! On auto if the slider temp is set to low or to high to the cars sensored temp then low and behold we have a gale blowing... So if the car water temp is cold.. we have cold air blowing... etc.. So really, the whole Climate control stuff IS crap..

Yep, thats what the S1 climate control seems to do, it's auto fan speed algorithm is a bit on the simple side, and goes something like this - if the cabin temperature is equal to the the preset temperature the fan speed will be slow, if the cabin temperature is lower OR higher than the preset temperature the fan runs faster, by the time the temperature difference is more than about 5 degrees the fan speed will be at maximum.

Thus when first entering the car with a large temperature difference between preset and actual cabin temperature the fan will immediately go to full blast and not slow down until the temperature is nearing the wanted temperature...problem is it completely ignores the actual temperature of the air exiting the vents.

Say the outside temperature is -5 degrees and inside the car is 2 degrees and you have the slider set to 25 degrees. Because the preset temperature is much higher than cabin temperature it will turn the mixer flap fully to hot, which is good, but it will then cheerfully put the fan on full blast to "warm" you up, despite the fact the heater is cold and you're getting blasted with -5 degree air for the first 10 minutes or so if you don't manually override it.

In NZ the opposite problem was more common - on a 25 to 30 degree summer day after the car had sat in the sun for a few hours the inside must have been well over 40 degrees, you'd get in, make sure the A/C was on, temperature set to 22 or below, start the car, only to be greeted with a blast of extremely hot air due to the fan coming immediately onto full blast - despite the mixer flap being on "cold" the air ducting in the car would be very hot and give you a good blast of unbearable hot air for a minute or so until the A/C could kick in and get it cooled down. (in practice you wind the windows down or set the fan manually to slow, you can't turn it off as that kills the A/C as well)

I had experience with a 94 and 97 S1 both with A/C and they both had the exact same behaviour.

On the S2 it seems to take notice of the temperature of the air exiting the vents before making its decision about fan speed. In the same early morning scenario it will set the mixer flap to hot, put the fan on the very lowest speed then wait to see what temperature air comes out. If the air coming out is actually colder than the current cabin temperature (when its trying to heat) it just leaves the fan on slow and waits patiently until the air coming gently out the vents is hotter than the cabin temperature and THEN starts to gradually crank the fan speed up. When the vent air is a lot hotter than cabin temperature the fan speed comes up to near full speed. Finally when the cabin temperature comes up near the preset temperature it slows down again. Much smarter, auto fan speed is based on ambient, desired, AND actual vent temperature. No blast of cold air in the morning and I presume no blast of hot air in summer either. The demist setting does override all this however and will bring the fan on fast regardless.

I also find the Auto setting doesn't work.. It will blow HOT, then stay hot to about 20deg then go straight to cold!! It doesnt regulate the temp at all...

One of your temperature sensors is not working then. Most likely the tiny fan that blows cabin air over the cabin air temperature sensor has seized - its in the little grill beside the clock. Without that fan there is a huge lag in the response of the sensor to changes in cabin temperature, which leads to the ECU not being able to regulate the temperature properly. (Or the sensor itself might be faulty)

It could also be the temperature sensor that measures the air coming out the vents not working, without this it can't regulate the mixer flap as it doesn't have any feedback on the temperature of the air exiting the vent.

If you've got a Lexia or access to one have a look at the live sensor data from the climate control, in particular all of the temperature sensor readings and the inputs from the driver controls, any problem with the sensors will be easy to spot.

There's 5 different temperature sensors - ambient (measures the air coming in through the bonnet scoop near the wipers) cabin (next to the clock) facia (air coming out the main dashboard vents) footwell vent, and evaporator. (drops to about 3 degrees with A/C on, otherwise a similar reading to the incoming ambient)

[citroenxm]

Ah Simon, interesting info there.

I have my own Lexia yes.. However, where is the "face Vent Temp Sensor"? I know its NOT in the face vents? I beleve its mounted further down somewhere??

I never thought about putting lexi on to look at the sensor readings, infact didn't know it did show all that. I know about engine ECU live data readout ETC, but never thought about the Climate ECU..

Something to do in the morning now..

[Northern_Mike]

Steady on guys, I wasn't intending to start a bun fight in here...

Considering how unreliable electronics in Citroëns are I can quite believe that some do work and some don't... and we know that there are at least two versions of the climate control A/C which changed over around the S1 to S2 transition...

I certainly notice the behaviour of the climate ECU in my S2 is very different to my S1, for example the S1 auto fan comes on at full blast in cold conditions before the heater has warmed up whereas the S2 sensibly keeps the fan very slow if the ambient temp is low and the heater has not yet warmed up, gradually increasing it when the heater core does warm up...

Maybe the auto A/C in demist mode only activates under certain combinations of inside and outside temperatures as well. Who knows... Relax everyone.

Way HEY.. allas, something else mine does NOT do! On auto if the slider temp is set to low or to high to the cars sensored temp then low and behold we have a gale blowing... So if the car water temp is cold.. we have cold air blowing... etc.. So really, the whole Climate control stuff IS crap..

Yep, thats what the S1 climate control seems to do, it's auto fan speed algorithm is a bit on the simple side, and goes something like this -

You say that, but the climate in the grey V6 S1 was spot on. Seriously, it was the best climate control in any car I've had. Absolutely bang on!

Weird!