Xantia 1.9TD Cooling Fan Set Points

[Zelandeth]

Evening all.

Something I would like to check this weekend is the correct operation of my cooling fans, especially given that the XUDs aren't fans (no pun intended) of getting too warm.

Now I confess to being a bit new to cars with this much electronic trickery, so my usual approach of "find the thermoswitch and read the number stamped on it" obviously needs a bit of an update.

Could someone let me know at what temperature the fans should kick in both at low and high speed?

Next question, is whether it would be viable to provide a switched voltage (12V I assume) to the relevant coil on the fan relay to allow manual control of the fan? It's one of those things that I generally like to have as a backup device. Or given the level of ECU control here now is that just pointless?

First thing though is I just want to leave the car idling for a while and see if the fans kick in and shut down at sensible levels.

Could someone note down the on/off values for me so I can check?

Guess I'll need to pay more attention to this as the fans I imagine are a bit quieter than the Saab's one which you can hear from the next street over and makes the whole car vibrate slightly when running!

Sure I saw a post on this the other day, but I can't for the life of me find it now...

[Hell Razor5543]

Does your car have air conditioning? If it does, and it is in working order, when it is switched on the two cooling fans should then spin up to high speed.

[Zelandeth]

Quick answer: yes it does, and no it isn't. Appears to have no gas in as it's out on the low pressure switch.

It's on the to do list...

[Jaf]

Mine has air con but the fans only come on to low speed when air con turned on. I thought that was normal? I only get high speed fans when the engine is very, very hot around 95. You can hear them, sounds like a train's coming!

[CitroJim]

Hi Zel,

No thermoswitch on a late Xantia... Good job as they were never very reliable...

One quick way of testing the fans basically is to disconnect the brown Bitron Sensor, located on the thermostat housing and is one of the two front sensors.

Disconnecting this sensor will make the fans run at high speed and they will remain so until reconnected... In disconnecting it you're simulating a 'failsafe' against this sensor going open-circuit. It protects the cooling and A/C by switching on the fans and having full cooling whatever.

This might be a way to do your emergency switch...

Making them run at half-speed with a empty A/C is a case of leaving the engine to get to the necessary temperature...

It can take a while this weather...

It's a good idea to test the fans as they are complex and long and happy engine life depends upon them being good. The XUD is very sensitive to cooling issues.

There's a few topics in this very forum about sorting unhappy fans...

And of course there's always my place....

[Hell Razor5543]

Then the most likely point of failure (according to what I have read here on the forum) is the fans that control the fans and their speed;

http://www.frenchcarforum.co.uk/forum/v ... =3&t=38231" onclick="window.open(this.href);return false;

[CitroJim]

Indeed James, the relays are a main cause of failure and also the motors themselves..

If one goes open-circuit or otherwise intermittent then the fans will not start up on slow speed as they are wired in series...

A Bitron Sensor Disconnect test will show if this is the problem as only one fan will start up. In fast speed they are wired in parallel..

The series/parallel switching to activate either half or full speed is accomplished by the trinity of relays...

I had a fan motor go intermittent on my Activa back in the summer.

A rough test of a suspect intermittent motor is to poke its fan blades with a stick. It might then be persuade to start up.

If it does then sticky brushes are the likely culprit and prima-facie this should be easy to sort but the motors are not really made to be dismantled with any great ease..

[Zelandeth]

Cheers folks, will have a look today.

Remember reading about the control relay, so will give that a poke if needed. Should be easy enough to sort so long as the coil is okay. Contacts can be cleaned, terminals reattached and springs replaced. Played that game many times with Lada headlight relays and flasher units (they make a passtime of dropping the flexible strap that connects to the floating contact).

Had to basically rebuild the motor control relay on the Sinclair C5 earlier in the year after it tried to kill me on the first test run. 250W of motor doesn't sound like much...it seems a lot though downhill with poor brakes when it won't switch off!

[Zelandeth]

Okay, brown connector removed - once I figured out how to get that swine of a spring clip off - and sure enough, no fan activity. Nor does poking either fan do anything. Time to check the relays.

Silly question...where physically are the fan relays? About to go rummage, so may answer the question myself in a minute...

[Hell Razor5543]

If you look at the mouldings around the fans you should see a triangular cover at the top space between the fans. This is (from what I have read here) where the relays, etcetera are to be found.

[Zelandeth]

Ah ha! Wondered if something could be hiding in there! Does make sense. Looks easy enough to get at with a couple of screws out as well.

[Hell Razor5543]

I would do some checking on the forum, as there are clear instructions on how to do this.

[MikeT]

I had the same fault (non-working fans) and traced it to a corroded wire connection in the harness that goes through the O/S wing. This is on a car I bought with failed glow plugs, failed head gasket, failed A/C clutch, failed thermostat and failed heater matrix (to name a few!).

What I'm getting at, is get those fans sorted before you use the car again or you could be looking at a whole heap of coolant related troubles in short time.

If it's any help, this is a snippet from my blog http://www.frenchcarforum.co.uk/forum/v ... &start=120" onclick="window.open(this.href);return false;

I logically tested from the battery lead to the fan relay, via the fuses and managed to eliminate some of the circuit. There's a break between the fuse box (F14) and the fan relay.

[Zelandeth]

Curiouser and curiouser.

We have power at the relays, and at least one of them is clicking when the Bitron connector is connected or disconnected. However no activity at the fans, irrespective of whether they were poked, prodded or bashed with a screwdriver.

Suppose one possibility is that both motors are duff. Will be doing a bit further digging once the rain stops.

I did spot this plug hiding down behind the offside headlight though, and a matching connector attached to the underside of the slam panel, the wiring from which as far as I can see disappears down towards the radiator. Should these be connected? Just how well they match up seems surprising if it is purely by chance. Not about to go plugging things in randomly though without knowing what they are...



Is this connector anything to do with the fans, or is it a complete red herring?

[CitroJim]

Zel,

If that connector is on the driver's side just under the slam panel then it's likely to be the connector to the bonnet tamper alarm switch. If you look in the offside bonnet latch you'll see a little plunger. This is the top of the switch that signals to the alarm ECU (the CPH) that the bonnet has been tampered with.

It's a bit temperamental in old age and often disconnected.

There's a similar one for the tailgate which gives even more trouble...