Bitron Unit for early Xantia

chasqui · Post by **chasqui** » 04 May 2009, 11:40

I have a Xantia 1.9TD SX from 1993. It has factory fitted air con.

I have been having problems with the fans not coming on at the right time or not at all, and the car overheats intermittently.

After reading all the various posts on similar problems, the only possible solution seems to be to replace the bitron unit. I have already checked relays, brown sensor unit, etc.

Because air con was only standard from P reg (mine is L), the bitron unit would have to be ordered thru Citroen in France (thru a UK dealer) The price quoted is £150 +vat. Had it been P reg or newer, it would be £52+vat. Needless to say, they are both not the same, I have tried!

Does any one know anywhere here in the UK that can either repair or supply a bitron unit, other than a citroen dealer?

I have tried 3 breakers yards, but of the few older xantias in them, none have air con, so no bitron unit.

Help please!

Many thanks

Post by **xantia_v6** » 04 May 2009, 11:53

Can you give a clue as to how to identify the early unit? I think I have a used Bitron, which came with some other parts, but I don't know what year car it came from.

You might also need to check the integrity of the wiring to the Bitron, as there seem to be cases of wires dissolving within the harness.

Post by **CitroJim** » 04 May 2009, 12:20

Welcome to the forum chasqui

I would agree with xantia_v6 here and look for rotten wiring before finally condemming the Bitron unit. The wires Citroen use are very poor quality and thise that run in the 10AV harness under the rad do suffer and this loom carries every feed from the engine bay into the cabin.

I have the complete wiring diagrams for the early Xantia with A/C and I will scan them and post them for you. They are scruffy as the book they are in is falling apart at the seams. Shows how good Xantia wiring is as that is by far the most used manual in my set!!!

Just before I post the diagrams, can you confirm that your Bitron is mounted adjacent to the engine bay fuse box and not down in the more usual inaccessible spot under the LH headlamp.

My documents indicate that this earlier system was used up until MY 1995 so L amd M plate cares should have this rare Bitron. The wiring looks very similar between the two variants.

Post by **CitroJim** » 04 May 2009, 12:56

Here are the diagrams applicable to the early MK1 with A/C:

These first three are the A/C proper..

A/C Circuit

A/C harnesses

A/C Component Locations

These next three are for the engine cooling fans...

Cooling Fans Circuit

Cooling Fan Harnesses

Cooling fan Locations

Note how pivotal harness 10AV is

Hope they help nail the problem. My book has now completely fallen apart scanning those

Clogzz · Post by **Clogzz** » 04 May 2009, 13:36

Welcome to our fan troubles, chasqui.

It’s not likely to be the Bitron, we’re indeed well used to pulling out rotten wires.
If you put contact 1 of the Bitron socket to earth, both fans should go to low speed, even with the key out.
If they don’t, it’s not the Bitron at fault.
If you earth contact 10 with the key set to accessory or ignition, both fans should go to high speed.
If they don’t, it’s still not the Bitron.

Oops, Jim !

I wrote this before I saw your last post.

Post by **CitroJim** » 04 May 2009, 13:48

Clogzz wrote: Oops, Jim ! I wrote this before I saw your last post.

No worries Clogzz

You have considerably added to the thread with the annotated diagrams and your tests. Very valuable stuff, that

You remain, as always, our fan supremo

chasqui · Post by **chasqui** » 04 May 2009, 15:10

What can I say. What a prompt reply. Many thanks.

To Xantia-V6.. Clogzz photos identify the unit and it's location. There are three numbers printed on it:

PP-TD30
CCT 6/TA
9616590480

There is also a mauve coloured "trim" at it's base, just above where the connector plugs in.

To CitroJim and to Cloggz.. Thanks for all the diagrams, photos and suggestions. Will be gowing thru them tomorrow and will post back the results.

Thanks again guys.

citroenxm · Post by **citroenxm** » 04 May 2009, 15:14

The unit is useually under the PASSENGER headlight, and Id agree with BROKEN wires aswell!

Ive done TWO series two cars now, and found broken wires around the battery tray.. The harness has a Plug join on the inner wing to the right of the battery.. it was between this plug and the control box were the wires had failed...

Rgds
Paul

chasqui · Post by **chasqui** » 04 May 2009, 16:29

Thanks Paul..

I'll definately be checking the wires in the morning. I've located my unit tho in/near the fuse box in engine compartment. Can't find anything in the wing. Are there two of them?

citroenxm · Post by **citroenxm** » 04 May 2009, 16:42

Hi.. no theres just one plug, BUT as you said, being a S1 before face left, the harness could be different laid out...

Good luck with yur workings...

Rgds
Paul

Clogzz · Post by **Clogzz** » 05 May 2009, 12:27

The Mk I also has the plug into the inner wing to the right of the battery.
That’s actually where I had a broken wire, just as per Paul’s post.
One wire to the temperature sensor was measuring 3 Ohms, and was causing the fans to intermittently come on for no reason.
The break was probably at a crimp into the socket in the inner wing.
Too much trouble getting in there,

so I made a bypass of both sensor wires around the inner wing connector.

Correction of mistake

in my previous post:
Earthing pin 10 by itself should only cause one fan to go to high speed.
It’s earthing both pin 1 and pin 10 together that should send both fans to high speed.

chasqui · Post by **chasqui** » 05 May 2009, 15:34

I've now tried all the suggested "tests", and can conclude the wiring is sound. The feeds are where they should be and the fans kick in when the pins are connected/grounded as suggested earlier.

So, does anyone know where I may find a used bitron unit for my early 1993 xantia? The numbers printed on the box are:

Bitron Video
PP-TD30
CCT 6/TA
9616590480

Thanks to all who have offered suggestions and advice.

Clogzz · Post by **Clogzz** » 05 May 2009, 16:01

The feeds where they should be; are they the supplies to the Bitron ?
Permanent 12V on pin 4, and switched supply on pin 15 ?

DickieG · Post by **DickieG** » 05 May 2009, 16:56

Bear in mind that there are three factory fitted versions of A/C on Xantia's that I'm aware of, two are common one's where the fan has an auto setting with numbers on the temperature control, with this version it changed specification very late in series one production, the later version giving greater control over temperature. The third version, called "Single air conditioning" did without the auto setting on the fan and had no control over cabin temperature, a very early 1993 VSX TD I owned was fitted with this.

Where I'm going with all this is be careful of where you are taking your information from, make sure it relates exactly to your car to avoid grief and unnecessary expense.

chasqui · Post by **chasqui** » 05 May 2009, 17:03

Hello.

Yes.. As far as I can tell. I have put the tester on pin 4 and I get a permanent 12v feed.

Pin 15 only gives a reading when ignition is on.

I don't really know what else I can do.

The other thing I haven't mentioned is that I have a permanent orange warning light in the temperature gauge. When I plug in another bitron unit, the light disappears but the fans are permanently on. I guess cos this other bitron unit is not the right one for my car. After a while the fans switch off. If I give them a tap they will come on again. So perhaps I have two faults? the bitron unit and the brushes on the fans?

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