Fans not kicking- overheating - a Bitron Snensor problem?

DIR · Post by **DIR** » 27 Jul 2006, 15:50

My Xantia ( 1.8I LX, 1998) is overheating. It would appear that the fans in the front are not kicking in, so on a freeway it is fine, but in traffic the temp goes up very quickly and if very hot, I need to stop and switch off. It also seems to use water although I never see steam coming out of the radiator cap - there is a deposit around one of the hose seals, which may be a leak.

I suspect that this is a problem with the switch which is referred to in the Haynes manual as the 'Bitron' switch.

Any ideas? Also

* How difficult is this to get to and check/change ( Haynes seem to
indicate that this is not easy!)

*If I let a garage do it, is it an expensive item ?

Many thanks,

DIR

3eme_attaque · Post by **3eme_attaque** » 27 Jul 2006, 21:33

electric fan switches here cost around £1 - £10 depending on the car, normally they are not too difficult to fit, especially if a screw in type at the top of radiator as you only have to drain that much of the coolant and then swap over. however i have not seen it on a xantia so couldnt really say, im sure one of the many xantia owners on here should be able to sort you out!

Post by **Peter.N.** » 27 Jul 2006, 21:35

It's just as likely to be poor contacts on the bitron and associated relays, if you can find out which ones, pulling them out in plugging in again will often effect a cure, if not, try unplugging and plugging all the relays that you can see.

It could also be the temperature sensor, again, I dont know which one, I only speak diesel XM.

3eme_attaque · Post by **3eme_attaque** » 27 Jul 2006, 21:40

Ah theres the proper advice! really shouldnt try and comment on cars ive never driven... 8)

Johnno · Post by **Johnno** » 28 Jul 2006, 13:16

I assume from your post that there are two fans on your car? If so, I believe they should always run together - either in series at half speed or in parrallel at high speed. If your car is aircon, they should run at half speed when the aircon is engaged.

I would suggest that the Bitron unit is reliable and unlikely to be the cause of your trouble. It's also a b****y pain to get at, requiring significant dismantling of the front area, as it is under the N/S headlight. First check relays and temp sensors as well as earths.

My Xantia fans packed up a few weeks ago on a crowded North Circular. After suspecting the Bitron, the problem turned out to be two (!) duff fans. They doubtless failed one at a time as the problem was worn brushes and it was only when the second one went that the temperature started to climb. They can be dismantled - with difficulty - but you are likely to damage them in the process. If needed, get replacements from a wrecker as even GSF quote £99 per fan and Citroen have three (??) types available from £110 to £230!!

Search on the Aircon section of the site and particularly for posts from "Clogzz" - very knowledgeable about this sort of problem.

Clogzz · Post by **Clogzz** » 28 Jul 2006, 14:58

Thanks for that, John,

and let's hope to see a good outcome for DIR.

If the car has air conditioning, then it has a Bitron fan controller.
If it’s got no air conditioning, then it’s a lot simpler, and the fault is probably the sensor switch on the radiator, and the Haynes diagram for ‘Turbo Diesel Cooling System’ shows all parts involved.
More ideas in these topics:

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

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

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

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

f00lzz · Post by **f00lzz** » 28 Jul 2006, 17:16

Shouldn't he disconnect the brown temp sensor plug first to ascertain whether or not the fans are at fault (A/C model)??

Clogzz · Post by **Clogzz** » 29 Jul 2006, 13:27

Oops !

Yes, f00lzz, but I wasn’t thinking of that because on the 4-cylinder petrol engine, especially the 1.8 with the large head, it’s impossible to reach it.
I’ve never seen or been able to reach mine.
We’ve had weeks of rainy weather here, and I think that the maggots got inside my brown connector, because when starting the engine after work on Friday, the overheat and STOP lights immediately came on with also the high speed fan noise.
Only way to get rid of it was to turn the air conditioning on, which sent the fans to the low speed.
All I can do is to squirt WD40 in the general direction of the brown sensor, with the ‘spaghetti’ appropriately curved at an angle, and hope that I squirt the target without seeing it.
On this page, Alan explains how he went about reaching the brown sensor on the 4-cylinder petrol engine:

http://www.frenchcarforum.co.uk/forum/v ... c&start=30

DIR · Post by **DIR** » 02 Aug 2006, 13:15

Thank you to all who have responded to my query. I have looked under the hood, and cannot really find any relays wires ( brown, blue, or any other colour,) that I could clean, short across or more like likely blow up the whole car.

What I have managed is to remove the font grill which exposes a large space in front of two very dead fans. Haynes says that I have to disconnect radiators hoses and tilt radiators to remove these fans, and that starts looking like a 3 or 4 spanner rating ! What I can hear are some clicks on the RHS which seems to me to be an attempt to kick in, but there is no movement in the fans. I did spray all the connections I could see ,as well as as much of the fans I could get to with a liberal dose of WD40, but no joy.

I must say I am very tempted to cut the blades off the fans, thereby exposing the radiators, and simply put a couple of cigarette lighter operated dashboard type fans in the open space. When the temperature starts to climb, simply flick a manual switch to bring in the fans ( or possibly just leave them running all the time.)

PS This is not a serious suggestion, but it is simple, (apart from cutting off the blades) cheap, and who knows may actually even work !!!) However, I think I will have to admit defeat and let the auto electrician handle it.

Johnno · Post by **Johnno** » 02 Aug 2006, 14:08

Don't give up just yet. If your car doesn't have aircon, diconnecting and tilting/removing the radiators isn't that difficult. As you have the front grill off, there should be a triangular housing between the fans. If so, this is the location of the relays. Not sure about the 1.8 but mine has three. Somewhat confusingly, the book refers to the left and right fans as though from the drivers seat. When you are looking at the front, the upper left relay controls the right hand fan and vice versa. The middle relay controls the high speed circuit. You can check the operation of the relays by removing them and connecting twelve volts to the appropriate pins (these are usually five pin relays - I think it's pins 1 & 2 but checkt the circuit diagram) and listening for the click of the solenoid. If operating, you can then check for a completed ciruit by using a mulitmeter.

If you can get to the back of the fans by doing the "tilting" you should be able to pull the moulding holding the two-pin connectors off each fan (as you may need to reach through the fan to squeeze the snap connectors inwards I suggest you disconnect the battery!) and you can then apply 12 volts directly to the each fan to check its function.

Assuming the above items are ok, it should be possible to short the output connector on the radiator thermal switch to simulate a temperature rise and to check that circuit.

These are basic checks that may yield results and are almost certainly what an auto electrician would do.

DIR · Post by **DIR** » 02 Aug 2006, 17:37

Thanks for the encouragement John.

I have gone through the first stage and removed and checked all three relays. All are working perfectly, giving healthy sounding clicks when 12 volts is put across pins 1 and 2. I am not sure how I would to check for a complete circuit, though.

Still no life from the fans when I turn on the air con. What is interesting is that there is a clicking sound coming from that area, and now that I know the sound of the relay, I am almost sure it is them.

The car does have air con, and there appear to be 2 radiators. The back one seems like it will tilt back quite easily (only two clips on the top), but the front one, (between the back one and the fans) is not described in Haynes. Also, Haynes wiring diagram (pg 13.33) only shows one fan (ref 1510, engine cooling fan) although the list of components shows both a RH (ref 1511) and LH (ref 1512) cooling fan. I have Haynes manual 3082

My gut feel seems to be that both of the fans have failed and I think need to be able to get to the back of them to check them as you suggest , with the direct application of 12V. I need a little more 'help' with getting to the back of them, as this does not seem to be as described by Haynes.

Many thanks for your help and vote of confidence

f00lzz · Post by **f00lzz** » 02 Aug 2006, 17:49

Have you checked to see if the A/C compressor clutch is engaging when you switch A/C on.... if it is... that may be the clicking noise you hear!! If it isn't then the fans won't be starting up anyway until you get the engine hot!!

DaveW · Post by **DaveW** » 02 Aug 2006, 18:12

It is possible to remove the fans through the front now that you have the grill off.
If you look in the centre of the blades part you see a small screw head.
This is a LEFT HAND THREAD screw (so turn it clockwise to undo).
Be careful when removing it as there is a tiny countersunk anti-shake washer behind it. Once undone you can pull the blade part off the motor shaft and, with a bit of jiggling, squeeze it out through the front.

You will now have (limited) access to the three nuts that hold the motor in place. I found that using a small socket and a mini swivel head 'breaker bar' it is just possible to undo the nuts.
The wiring is simply clipped into one of the three plastic struts that support the motor and the plug at the end of this will be on the bottom of the support. On my car this was very difficult to remove and I had to carefully lever it out with a screwdriver - didn't seem to harm it though.

With everything disconnected you can wangle the motor out through the front.

Having said all that, I reckon that there is better than an 70/30 chance that the fans will be OK and I would suggest that you do more checking of the electrical circuits around the fan motors before scraping your knuckles pulling the fans.
The links that Clogzz posted contain all the information to track down the fault.

Dave.

Johnno · Post by **Johnno** » 02 Aug 2006, 20:05

I agree that there is mileage to be had in some further checking of circuits. But my own experience of two fan failures suggests that before too much longer you are going to have to establish if the motors actually work. Given the amount of dismantling, this is something you may wish to undertake yourself (with a friend to help), rather than paying £40 odd per hour to someone else. Allow around 3-4 hours for the first attempt. I also suspect that having neither fan working at high engine temp (more than 100c) is - as far as the circuit diagram is concerned - not possible unless you have a Bitron fault, temperature sensor fault or double fan failure. I'm prepared to be shot down on that statement!

With air-con, you will have difficulty getting sufficient clearance by merely pushing the rads away due to the extra radiator and there is a risk you will fracture a refrigerant pipe - and you really don't want to do that.

I have the same Book of Lies as you and I suggest you use the diagram in section 13.34 referring to the Turbo Diesel models. This will be much closer to your setup. Just to show that you shouldn't trust these books too much, a mate of mine has the later manual for his 2.1 and it includes the Bitron in the circuit diagram, but these items were fitted in pre-'98 models as well. You can, after removing the battery, get the connector off the Bitron by pulling out the sliding locking bar, coloured orange on mine. You can then use pins 1 & 10 as earths to simulate the effect of the unit.

The fans are held on with 3 x 10mm nuts but before going ahead, take the connector off the radiator switch (should be right-hand side as you look at it) and connect between pins 1 & 2 on the wire. This simulates high temperatures and allows the fans to operate in parallel (ignition on). May well indicate if at least one is working.

One last point: If you decide to remove the bumper and headlight mounting cover then in order to move the air-con radiator you may need to disconnect an alloy pipe holding block on the left lower side of the rad. It is held on by two deep-set cap screws. I think they were 8mm hex. Difficult to do but perservere.

Best of luck!

f00lzz · Post by **f00lzz** » 02 Aug 2006, 20:15

The fans are held on with 3 x 10mm nuts but before going ahead, take the connector off the radiator switch (should be right-hand side as you look at it)

A radiator switch!! Must have missed that one.. I thought the temp control would have been on the thermostat housing (brown plug) in an A/C model

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Fans not kicking- overheating - a Bitron Snensor problem?

Fans not kicking- overheating - a Bitron Snensor problem?

Duff Fans - Thanks All

still Hanging i there