Xantia rad fans.

Brigsygtt · Unread post by **Brigsygtt** » 22 Oct 2009, 19:03

Rad fans have officially gone crazy on my xantia.

They are coming on full belt at random, i.e on startup, 60 deg on temp gauge etc. The engine is running fine & not overheating, coolant temps are spot on.

My xanita has aircon which is not working, due to bypassed compressor/no gas etc.

Could it be something to do with the a/c system? if i pop the aircon button on it still forces the fans to cut in so im assuming the sensors are still working in a fashion? The demister switch isnt set on windscreen either.

Anybody had the same problem/got a solution? Its annoying me as the engine is hardly up to temp most of the time & the hovercraft noise gets on my nerves!

MikeT · Unread post by **MikeT** » 22 Oct 2009, 19:12

One of the plugs (brown?) - can't remember which one so try all (three?) - attached to the sensors on the thermostat housing can get a bit loose over the years. Try cleaning and refitting them. The logic is, when the ECU isn't sure it's not overheating (ie it doesn't get a temp reading from the sensor) it puts the fans on half-speed for a couple of seconds then sends them full speed as a safety precaution.

Unread post by **CitroJim** » 22 Oct 2009, 19:52

Yes, that's it Mike

The Brown Bitron sensor on the thermostat housing. It works opposite to any other sensor and you're bang on that the fans come on as a safety precaution if anything goes wrong with the Bitron such as the sensor going open-circuit. Dirty contacts on it (quite common) fools the ECU into thinking it has gone and put the fans on.

The Bitron is easy to get to in all but the Activa. here it lives right at the back of the engine and is all but inaccessible.

If not the sensor, the Bitron ECU contacts can be at fault. The ECU is very inaccessible as it lives under the NS headlamp under the front panel and needs the front of the car removed to get at it

Brigsygtt · Unread post by **Brigsygtt** » 26 Oct 2009, 12:48

Sorted, the plug was loose on the brown bitron sensor. Cheers all

nagib77 · Unread post by **nagib77** » 19 Nov 2009, 15:44

Where is that bitron sensor? How can I find it and how it looks like?
I have problem with A.C on Xantia. It starts and then after 20 sec stops by itself. After that it starts agaim, and so on... I will check bitron sensor first, but where??? Does someone has product number of bitron, so I can find it in cataloge?
Thanks, Nagib

VertVega · Unread post by **VertVega** » 19 Nov 2009, 16:24

For bitron you can check this thread --> bitron, aircon, rad fans ... Cloggz has sent nice pic attachments.
Bitron box is seen in the first pic of the three and connector in the third pic.
Forum "Search" is very useful.
(Also in my post in above link, 3 sensors on the thermostat house are seen.)