HDi Fans again! (sorry!)

pwatson · Post by **pwatson** » 18 Aug 2006, 18:40

I'm a bit stumped - it doesn't take much! - and i'm sorry for raising this topic again, especially as I have spent most of today reading all the previous posts and references on problem fans. This is in a 2000 HDi Exclusive 110 with air con and climate control.
To put you in the picture, last year on holiday in France (towing a caravan) we got the flashing temps and stop light. I investigated ie looked under the bonnet, found the three relays between the fans, pulled them out, cleaned contacts etc and put them back in. At first no change, only right fan (looking at front of car) was switching on at fast speed. Then I tried swapping the relays since they all looked the same and had the same number on them, and they started working "properly" ie, they both switched on low speed with the air con, when engine got very hot they went to high speed. All was well until a couple of weeks ago on hols-flashing light and stop. So I repeated my "treatment". Swapping relays, cleaning contacts etc. One time both fans did come on but then back to just the right one on fast speed when air con on. After which we only used a/c sparingly, and each time got the flashing light for about ten flashes and then r/h fan cuts in and light goes out. No light when travelling above about 40mph (because of airflow?).
This morning I thought I would replace all three relays (only about a fiver each at GSF) but it has made no difference. I have tried some of the solutions recommended by the many knowlegeable people on here (mainly in response to Suzie) but no luck because:-
1. The r/h relay pin 1 is not live on my car with ign off or on but pin 3 on right and left relays is.(according to my little electrical test screwdriver thing)
2. I can't find the "radiator switch". I can find a grey socket with 3 thin wires (2 green and 1 white) attached to right side of radiator by a plastic bracket but it is nothing like the temp sensor "plug" that screwed into the side of the radiator on my old BX (had to replace that 'cos fan not working)
3. Can't find any "plug" or sensor on the thermostat housing.
Sorry if some of the things I say are a bit "thick" but I'm a bit lost here!
Any suggestions or help gratefully received.
By the way, no sign of car overheating while towing, needle never above 90, no flashing lights even when ambient temp over 30 and car towing up steep hills in low gear. Just taken car for a run and left standing for half an hour but temp won't go above about 85 so don't know if fans switch on low when engine gets hot! Even in jam on M1 yesterday, temp never went above 90.
Sorry for long post

Clogzz · Post by **Clogzz** » 19 Aug 2006, 13:52

The 2000 HDI has a Bitron controller for the fans.
Looks like the radiator switch was only used on very early air-conditioned Xantiae.

Pin 1 of the left fan relay must be live all the time.
Pin 1 of the other two relays are live only when the ignition is switched on.
The ‘plug’ on the thermostat housing is the brown one of 3 electric temperature sensors.
It senses the temperature to tell the Bitron to switch on the cooling fans, at low speed first, then at high speed when the engine is close to overheating.
The contact and wiring to this plug go intermittent, and cause the STOP and overheat lights to come on for no reason.
You can check on the operation of the low speed by switching on the air conditioner.
That causes the fans to go to the low speed, and stay there for all the time that the aircon is on, unless some emergency mode sends them to high speed.
Plenty of reading matter here:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=19090

http://www.frenchcarforum.co.uk/forum/v ... hp?t=18965

http://www.frenchcarforum.co.uk/forum/v ... hp?t=14682

http://www.frenchcarforum.co.uk/forum/v ... hp?t=17012

http://www.frenchcarforum.co.uk/forum/v ... hp?t=18871

http://www.frenchcarforum.co.uk/forum/v ... hp?t=19296

http://www.bxclub.co.uk/forum/viewtopic.php?p=6857

http://xu10j4r.free.fr/xantia/notexantia.pdf

pwatson · Post by **pwatson** » 19 Aug 2006, 16:20

Clogzz,
Thanks for the reply, much appreciated.
Just been out to check again. Definitely pin 3 that is live on left and right relays with ignition off (ie, top centre vertically aligned pin, not middle row r/h pin.)
I found the temp sensor (Sonde de temperature d'eau)with the help of my "Revue Technique" (French "Haynes") - it's a blue plug and virtually inaccessible due to air filter box and pipe and a couple of heater pipes and a couple of other plugs. Eventually managed to get at it even though 3 hands were needed but only space for a couple of fingers and a screwdriver to prise gently! Unplugged it, gave it a spray with connector cleaner and re-plugged and replaced the various other bits.
Started car, switched on a/c and TWO FANS on slow!!! Success!! Switched off a/c, left a minute or two, switched on A/C again, b*****! Flashing light and right fan on fast, left fan not working again, but then, after a minute left fan came on slow and right fan also on slow - so maybe success, maybe not!! Will wait and see how it behaves over next few days, but it does seem a bit erratic!
Can't find any reference to Bitron in Revue Technique - any idea where it might be on the HDi? I suspect it might be the brown connector next to the blue one, and which was really totally inaccessible!
Thanks again for you help
Best wishes
PhilW

f00lzz · Post by **f00lzz** » 19 Aug 2006, 17:01

Pretty sure that the Bitron plug which controls A/C is located in the same place on all A/C Xantia's... almost impossible to get too... remove nearside headlight and you can see it and remove and clean the plug... to replace it I suspect requires further bodywork removal...

pwatson · Post by **pwatson** » 19 Aug 2006, 18:57

Thanks f00zz, will investigate tomorrow - suddenly gone very dark and raining heavily here!

Clogzz · Post by **Clogzz** » 20 Aug 2006, 14:36

Pins 3 of both the left and right fan relays are always live because they're permanently fed by the two large 40 Amp fuses.
That’s a good sign, meaning no fault there.
Pin 1 of the left fan relay must be always live too, because it’s fed from an unswitched 5 Amp fuse, probably F5 under the bonnet.
If not, you won’t have the low speed, and you’ve got the DaveW fault:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=18965

Didn’t know that the sensors were inaccessible on the HDI.
They certainly are on the petrol cars, so much so that I've never seen mine.
The blue sensor, I think, operates the temperature gauge only.
The brown one operates the fans, via the Bitron.
There’s a third one, don’t remember the colour, probably going to the injection CPU.
On the petrol car that I have, the Bitron lives in the fuse box, very handy.
No chance of that on the HDI, and here are pictures to confirm f00lzz’s post.
You may need to remove the battery just to see the Bitron.
Since you read the ‘Revue Technique’, here's more French in this 4-page topic from ‘Planète Citroën’ with very good pictures:

http://www.planete-citroen.com/forum/sh ... php?t=8530

pwatson · Post by **pwatson** » 21 Aug 2006, 21:05

Clogzz,
Thanks for your advice (and patience!) I shall investigate further!