Xantia fans spinning flat out

Clogzz · Post by **Clogzz** » 15 May 2005, 19:09

Does anyone know how to reach the sensor with the brown plug on the thermostat housing to experiment with this fault ?
It's a contortionist's job.
A similar German site has a story about removing the air intake from underneath it, but I don't affect enough German to fully understand.
There are two separate 'spinning fans' faults.
One is where both fans spin flat out even when the ignition is turned off.
There are two 40 Amp fuses mounted to the inside of the passenger side mudguard near the main fuse box.
Removing the second fuse as seen from the front of the car fixed this fault in July of last year.
The other 40 Amp fuse, the one closest to the front of the car has to stay in, otherwise the fans will never spin at any speed.
Thanks for your troubles...

Post by **Peter.N.** » 15 May 2005, 22:55

Sounds like you have a duff relay, contacts welded together, on the XM they are behind the left headlight, I suspect yours might be in the same place.

Clogzz · Post by **Clogzz** » 16 May 2005, 18:31

The first fault is where the 'STOP' and 'overheat' lights come on at the same time for no reason and sometimes causes the fans to spin flat out.
The lights can come on without the fans spinning.
The fans can also spin fast without the warning lights coming on.
Turning on the air conditioning always cures the fault.
I got told that it was a faulty sensor on the thermostat housing...the one with a brown plug or wire.
The second fault is the one cured by removing the fuse.
The relays are in a box also behind the passenger headlight.
Will experiment a bit more and report the findings.
And...thanks for your troubles.

Post by **Peter.N.** » 16 May 2005, 19:43

A faulty sensor would cause the lights to come on but I would have thought that the fans should only be switched on by the sensor when the ingintion was on. You can check by shorting the two leads on the sensor together with the ignition off, if this starts the fans it could be your problem, if not try the same with the ignition on and the fan should start up. You can check to see if the sensor is faulty by disconnecting it when the fault is present, if faulty the fault shoud dissapear with the sensor unplugged.

Post by **RichardW** » 16 May 2005, 20:51

Nope, if the Bitron unit that controls the fans detects sensor failure (open circuit) it puts the fans on full, regardless of the state of the ignition (this is why you must not put your hands in amongst the fans unless the battery is disconnected, they can start at any time!). Pull the plug off the sensor (easy, it's right on the front of the thermostat housing), and measure the resistance of the sensor. If it's open circuit, the sensor is shot. If it is giving a reading, and this changes with engine temperature (measure it hot and cold) then the sensor is working, and there must be a break in the wire, or the Bitron controller itself is faulty. Try measuring the sensor first - changing it should be fairly easy.

ItDontGo · Post by **ItDontGo** » 16 May 2005, 22:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RichardW

...this is why you must not put your hands in amongst the fans unless the battery is disconnected, they can start at any time...
<hr height="1" noshade id="quote"></blockquote id="quote">
What are the chances? With some of the posts on here I suspect people ought to be more concerned about crashing their cars than losing a finger in a freak cooling fan accident.

Clogzz · Post by **Clogzz** » 17 May 2005, 18:12

RichardW,
Are you very certain that the sensor is at the front of the thermostat housing ?
I'm supposed to think that it's at the back, where it's impossible to reach it.

Clogzz · Post by **Clogzz** » 17 May 2005, 18:32

PeterN,
The fault where the lights come on and the fans spin only occurs while driving, including sitting at traffic jams, when it's more likely to do it as the temperature starts to rise.
The fans can start spinning for a few minutes at the low speed after switch-off because of rising heat...that's normal.
I've also had a fault where the fans were flat-out even with the engine turned off in the cool of dark last winter.
Removing a fuse fixed that for good and I haven't been back to it since...see previous posts.
There is also a fault where the passenger side fan spins flat out and the other one is stopped.
That fault's gone away for now.
It must be in the relays above the fans.
Access necessitates removal of the front grill.

Post by **Peter.N.** » 17 May 2005, 23:22

I stand corrected, my only experience is with XMs, Xantias seem to be different, so dont take any notice of me.

Clogzz · Post by **Clogzz** » 18 May 2005, 17:16

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Peter.N.

I stand corrected, my only experience is with XMs, Xantias seem to be different, so dont take any notice of me.
<hr height="1" noshade id="quote"></blockquote id="quote">
Peter,
Thanks for your troubles.
Double checked and all sensors are at the back, out of reach.
The only plug at the front goes to the distributor.
The Andispares 'air conditioning forum' has a link to the Peugeot 306 electrics map that it says is the same as the Xantia's.
At least I will be able to do some map reading.
So, I'm likely to be back soon.
Thanks again.