Weird cooling fan and Xantia brake bulb puzzle

JamesQB · Post by **JamesQB** » 17 Jun 2004, 05:01

Hi everyone,
Let's start with the weird cooling fan trouble on my Xantia 1.8 16V. Get home after a drive, engine at normal temperature according to gauge in dash. Park up, switch off engine and few minutes later the radiator fan comes on and stays on for ages. To stop it, we go to car and insert ignition key and turn ignition on to the setting that is just before engaging the starter. The fan stops and all is well for 5 minutes or so, then it goes on again, all the while the engine is getting much cooler anyway from the time passing and gauge says it's well below normal operating temperature.
When driving, car never goes past normal temperature range and radiator fan never comes on, probably because of this. The trouble only begins when the engine is stopped and left for a few minutes. If one drives it again while this trouble is ongoing, it stops happening while car is running. I just can't work it out and nor does the Haynes manual help with finding the relevant parts or listing what parts govern it all. It says the temp sensor is in the radiator - it isn't (perhaps that's the trouble!) I can't find it anyway. Any ideas?
Secondly, I've had the rear brake light stop working on both my Xantia and my parent's one. It's happened 3 or 4 times in my parent's car and 2 to my own. The bulb will need replacing and it's because one metal arm holding the filament for the brake light (normal rear light filament always fine) has melted and the filament is no longer touching it. For it to happen with both cars, same bulbs and same filaments, it makes me wonder what the trouble is other than dodgy French electrics. Two bulbs in two months in same light. What's happening to cause that arm to melt? Any ideas here?
I'll leave you all puzzling... [:D]
James [8D]

oscarloco · Post by **oscarloco** » 17 Jun 2004, 06:44

About your second problem, it could be that your light bulbs are of inferior quality. I had the same problem with my former car, everytime I used Taiwanese bulbs (VERY cheap) they would last very short and then, they would melt and because they were of the 2 filament type, end up with only brake light or position light.

uhn113x · Post by **uhn113x** » 17 Jun 2004, 13:16

James
It can only really be the bulbs themselves. Were they all from the same supplier? The rods that hold the filament are usually plated steel, which would need to get white hot to melt, and you could simply not pass that sort of current through a 21W bulb without the filament vaporizing!
Mike

JamesQB · Post by **JamesQB** » 17 Jun 2004, 16:33

Thanks both, it seems it's badly manufactured bulbs the trouble then. One of the cars is in Spain and one is here in the UK, so the bulbs weren't from same supplier but may have both either been cheaply made ones or the same make sold in both countries. Interestingly, the bulbs weren't originals in the car, they were replacements put in after normal bulb failure (filament falling apart) so that lends weight to this idea.
Now, the first trouble, does anyone have any ideas with that as it's becoming a pain and for fear of a flat battery, we're continually running outside with ignition key in hand to stop the fan spinning... I removed a relay to stop it coming on at all but with the heat lately and traffic jams in this little town infested with season tourists, the car started to get very hot and there was then no radiator fan to help cool it down so relay is back in again!

Post by **RichardW** » 17 Jun 2004, 16:45

James,
Does it have air-con?

andycarter · Post by **andycarter** » 17 Jun 2004, 23:32

If you just leave it alone, does the fan stop eventally?

egg · Post by **egg** » 18 Jun 2004, 02:16

Re the fan. If you have aircon the problem is with the bitron unit. It lives under the drivers headlamp. It will need replacing or cleaning. My 2.0 16v had the same fault as yours. It then got worse. The fan came on even when the car was cold - and never went off! Mine does not have air con thus no bitron unit. I took the advice of the main dealer and sprayed every relay/black module near and around the drivers headlamp(ON(one apparently controls the fan) and the brown connector on the thermostat housing a good squirt with duck oil. Solved the problem, and still ok. Hope this helps.

JamesQB · Post by **JamesQB** » 18 Jun 2004, 16:20

Hi, this car doesn't have air-con. We've left it to carry on before to see if it turns off, but after an hour we began to worry about the battery draining. However, on occasion it has turned otself off after 10 minutes or so. But it's intermittent - it's sitting outside now after a drive quite happy, no problems.
egg, funnily enough I removed the black relay from in front of the headlight area to stop the fan coming on at all, as I wrote above, and since I replaced it, the fan has behaved. The pins were filthy on it so while off I cleaned them as I tend to do with anything that needs it. I might have inadvertently solved the problem!
Thanks everyone,
James

SGould · Post by **SGould** » 18 Jun 2004, 18:34

I had exactly the same thing with the fan (and have the same Xantia but 97). Took it to a local garage who specialise in Citroens and it was fixed very quickly and cheaply. A new 'switch' was required.

jkirkwood · Post by **jkirkwood** » 18 Jun 2004, 20:02

Yeah, and the motor trade want us to accept electrical systems for other things - power steering, drive-by-wire steering, braking and the like. I'm just glad those systems aren't safety critical. (ironic humour)