xantia dual fans - how should they work

stevecritchlow · Post by **stevecritchlow** » 30 Aug 2005, 12:23

While trying to work out the source of a cooling problem on my 2.1TD Xantia, I unplugged the bitron sensor. My understanding is that this is a standard test of the sensor as it should put both fans on at full speed. The fans did turn up to full speed, but when I looked at them only one was running.
I have no knowledge of the way the fans should run, so.....
- Am I right in assuming this means one of the fans is not working, and that this is probably the reason that my car sometimes gets very hot on a run? Is there ever a reason why only one fan should run?
- At what temperature should the fans come on at (low and high speed)?
- If your advice does indeed suggest one of the fans is fautly, what are the likely causes that I should work through to cure?
thanks for any advice
Steve

Post by **RichardW** » 30 Aug 2005, 12:51

"- Am I right in assuming this means one of the fans is not working,"
Yes - the one that doesn't run
" and that this is probably the reason that my car sometimes gets very hot on a run?"
Unlikely, see earlier post about inefficacy of fans above 30 mph
"Is there ever a reason why only one fan should run?"
No
"- At what temperature should the fans come on at (low and high speed)?"
On my VSX they come on low at about 87°C indicated, but then mine runs at around 75°C indicated, which suggests a thermostat problem, or a slight mismatch on the gauge. I've never got it hot enough to get them on high.
"- If your advice does indeed suggest one of the fans is fautly, what are the likely causes that I should work through to cure?"
It either means the brushes are worn out, or there is a fault with the relays. You will need to get to the relays first (can't remember where they are, but probably behind the grill somewhere) and see if there is any corrosion or other troubles, then try 12V direct to the non running fan, after that it will be fan removal for strip down and repair (there's a post from AlanS somewhere about doing that). Warning - getting the fans out is typical Citroen 'fun'!!

rory_perrett · Post by **rory_perrett** » 30 Aug 2005, 17:20

Go for the relay's first. Just had a problem with my 2.1TD down to corroded connectors on the relays.
On my 1998 Series 2 model they are located between the two fans. Access comes from removing the front plastic panel and then the relays are in a triangular shaped box.
Have a look at this thread http://www.andyspares.com/discussionfor ... C_ID=14226
The www.peugeotlogic.com site was a great help to me.
Good luck
Rory

Clogzz · Post by **Clogzz** » 30 Aug 2005, 20:16

Both fans always have to do the same thing: both stopped, both at low speed, both at high speed.
At low speed, they're in series, so if one is faulty, neither will spin, causing the temperature to rise above 90ºC.
At low speed, only one relay is energised, at high speed all three.
They can be reached by removing the front grill only.
It's tight, but feasible.
See map on link:http://www.peugeotlogic.com/workshop/ws ... fanop1.htm

stevecritchlow · Post by **stevecritchlow** » 30 Aug 2005, 20:18

thanks guys, thats really useful stuff. I'll look at the car tonight, and come back with any developments
Steve

Clogzz · Post by **Clogzz** » 31 Aug 2005, 20:44

This link could be of use for its pictures.
The Bitron location is for diesels only.
On petrols, it's under the fuse cover.
The site allows for automatic translation at the bottom of the page >>> Traduire cette page >>> Français à Anglais >>> Traduire.
http://www.planete-citroen.com/forum/sh ... 530&page=3

stevecritchlow · Post by **stevecritchlow** » 05 Sep 2005, 13:13

Thanks for all the help folks, it was the motor on the nearside fan which had packed up. I ran the car up to 95 degreees and jumped out to look at the fans. The offside one was working so, that menat it had to be the motor.
Just to make you smile, my local Citroen main agent quoted me £218+vat for this part!!!!! Cash in advance and three day delivery. Its cheaper just to let the head gasket blow up!
Fortunatly GSF do one for £69 (and had it in stock) which quite frankly is enough for a simple motor, but compares very well to Citroen ridiculous price

oscarloco · Post by **oscarloco** » 05 Sep 2005, 21:15

Citroen parts are ridiculously overpriced. Good side is, quality is very good.

davek-uk · Post by **davek-uk** » 07 Sep 2005, 15:19

"Citroen parts are ridiculously overpriced. Good side is, quality is very good." That's odd really isn't it - as the cars are cheap and the quality is poor!!!! [:D][:D]

Rostami · Post by **Rostami** » 07 Sep 2005, 20:18

Sorry to barge in...what is the BITRON?

rossnunn · Post by **rossnunn** » 08 Sep 2005, 03:35

Mothers new exclusive estate's fans run at variable speeds to each other, one running at full tilt, with the other running at normal then switching up to a higher speed then both shutting down or running very slowly. It's probably something to do with all the aircon/climate control gizmo's inside. When they are both running at full speed I'm sure it's gonna start sucking in small furry animals!

Clogzz · Post by **Clogzz** » 08 Sep 2005, 16:48

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

what is the BITRON?
<hr height="1" noshade id="quote"></blockquote id="quote">The Bitron is the electronic fan control unit.
It is often blamed for erratic operation of the cooling fans, but the main cause of fan troubles is the wiring from the brown temperature sensor on the thermostat housing to the Bitron input.
In France, this problem has been the object of a recall, but everywhere else, we're on our own.

Post by **c.morewood** » 17 Sep 2005, 04:07

Do the fans run all of the time? On my Xantia Mk2 they always run from start up to shut down.. always have done.. I would be interested to know if its the same with all Xantia Hdi's.
Chris

rory_perrett · Post by **rory_perrett** » 17 Sep 2005, 14:37

The fans should only be on when they are needed, unless I have the aircon on mine only come on when I'm in the rush hour queues.

Clogzz · Post by **Clogzz** » 17 Sep 2005, 16:15

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

On my Xantia Mk2 they always run from start up to shut down.. always have done..
<hr height="1" noshade id="quote"></blockquote id="quote">Probably that the air conditioning switch is on all the time.
With the aircon off, the fans don't normally spin.
They start spinning at the low speed when the engine temperature reaches about 90ºC, or when the aircon is switched on.
The high speed is for when the engine gets close to overheating, or when the system is deranged, which is quite often.
Therefore it's possible that someone previously fiddled to have the fans spin at the low speed all the time to bypass the troublesome fan control system.