Xantia Cooling Fans

howzat · Post by **howzat** » 14 Oct 2006, 20:49

The cooling fans on my 1.8 16v Xantia seem to run unnecessarily before the engine warms up. I am trying to find the thermostat which controls them. Heynes manual is uselees in this regard. There does not appear to be anything on the radiator but there are three likely looking devices on the engine thermostat housing. Anmy suggestions grarefully received.

Stempy · Post by **Stempy** » 14 Oct 2006, 21:33

Does it have aircon?

Clogzz · Post by **Clogzz** » 15 Oct 2006, 14:48

You must be a contortionist to be able to see the ‘three likely looking devices’.

Unless they’re at the front of the thermostat housing, unlike on the 2.0 engine, where they’re at the back, out of sight, and out of reach.

The most likely device is the brown one; it senses the temperature to control the cooling fans, for both fan speeds.
If the contact is bad, the resistance is increased, and the fans will spin unnecessarily, first at the low speed, then at the high speed.

If the car has air conditioning, it also has a ‘Bitron’ control box to operate the fans.
If you’re lucky, the Bitron is in the fuse box under the bonnet.
The Bitron pins 7 & 14 are the input from the brown sensor, and become intermittent.
Take out the retaining spring that holds the Bitron plug, and wriggle it in and out a few times to scrape the contacts.
Leave the retaining spring out for now, so as to be able to repeat the experiment until you’re sure that it’s fixed.

On many models, the Bitron is under the passenger’s side headlight.
If that’s the case, you can start rehearsing from the dictionary of swear words.

howzat · Post by **howzat** » 16 Oct 2006, 23:19

Yes it does have aircon, but it behaves as described even with air con off

howzat · Post by **howzat** » 16 Oct 2006, 23:23

Thank you cloggz, most informative . Yes the three "devices" are at the front on this model which is a 1.8

howzat · Post by **howzat** » 20 Oct 2006, 20:39

Your warning was justified Clogzz, the Bitron is under the headlamp and to get it out you need to dismantle the front of the car! It would not be so bad if you could unclip it but its bolted down. However I did manage to take the plug out and squirt it with switch cleaner but this did not seem to help. If I disconnect the brown plug the fans switch to full speed so some sensing is going on. I suppose the next step would be to replace the brown sensor. At present it measures 1,900 ohms with the engine cool. Various sensors are listed by GSF and Eurocarparts but its difficult to know which is which. You dont by any chance have a part no. for the brown sensor?.Thanks for your help.

Clogzz · Post by **Clogzz** » 21 Oct 2006, 14:23

At cold, the brown sensor is 1800 Ohms, so 1900 will be normal when ‘cool’, and bad contacts along the way are more likely than a faulty sensor.
It’s also normal that the fans go to the high speed with the sensor disconnected, because then the resistance is ‘infinitely’ increased.
Since the Bitron is at the front, the loom passes through the inner wing, with a connector looking like a diagnostic socket coming out of the inner wing near the battery.
The intermittency or bad contact is likely to be there.
That connector slides to open it.
You may try to insert a shunt resistance where you can along the way, to test where it affects it all the time, meaning the fans staying still until the temperature gets close to 90ºC.
You may also be able to reach the Bitron by removing the battery and headlamp.
Don’t know the GSF and Eurocarparts numbers, but will edit them in here if and when found.
The Citroën part number for the brown sensor is 1338 55, item 16 here, though more likely to be mounted in the centre on an air-conditioned car:

http://www.citroen-pr.net/catalogues/il ... 36085C.gif

And more horror scenes caused by fan troubles:

http://www.planete-citroen.com/forum/at ... 1160420735

Edit at 3:45 PM:
Not finding at GSF, only seeing the radiator sensor switch at £8.50.
Euro Car Parts, part Nº 22473500G TEMP SENSOR AIR CON MAROON GENUINE Temp Sender Unit £16.28.

paulbx · Post by **paulbx** » 23 Oct 2006, 17:03

challenged for pwd..

Clogzz · Post by **Clogzz** » 24 Oct 2006, 13:47

Oops !

Thought it came by itself when logged out of both here and there, but it’s actually coming from the browser.
Here it is:

howzat · Post by **howzat** » 24 Oct 2006, 20:31

Thank you Clogzz for all that useful information. As the aircon and temperature control systems seem to be connected I tried removing the plug from the top of the aircon rec/drier. Hey Presto the fans stopped running until temp reached 90 C where they cut in and out as would be expected. This seemed to show that the brown sensor was working correctly.
It appears that the device (yet another device!) on top of the drier is a two pole pressure switch. A red wire and a white wire go to one switch and two green wires to the other. The red/white switch is closed with everything switched off and the two greens are open.
When I compare this with my XM of similar age I find a similar set up but in this case the red/ white switch is open and the other is closed!
I have a wiring diagram but this is difficult to decipher . It would seem that the pressure switch is telling the various cpus that the aircon is working and hence the fans are switched on.
I am doing a few more checks before condemning the switch as I think changing the switch will mean regassing the aircon.
Thanks again - Cassmo

alan s · Post by **alan s** » 24 Oct 2006, 22:32

No Cassmo, the switch can be changed without loss of refrigerant as it screws into what is basically a Schraeder valve similar to the one on the tyre of a car; just screw it out and screw the new one in.
Basically the switch you will find will have 3 values printed on the top of it and if the local Citroen man wants an arm and a leg for a new one, try a refrigeration/air con repairer for a new one that shows the same or close to similar values shown in bar.
It will have a pressure for the ability to cut in (central figure) one for a low pressure which cuts it out if the pressure drops to that figure and another higher figure which sets the fan at full blast in the advent of an overpressure.
It's a 5 minute job to replace and no special tools are needed.

Alan S

howzat · Post by **howzat** » 25 Oct 2006, 18:41

Thank you Alan, that is really helpful info.

howzat · Post by **howzat** » 01 Nov 2006, 20:09

Obtained new switch from www.fastcool.co.uk at £26. Now fitted and everything working perfectly. Thanks for all the help.

French Car Forum

Xantia Cooling Fans

Xantia Cooling Fans

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