Citroen XM Forum

I knew problems would eventually rear their ugly head but it's been 2 years of trouble free continual use so I really can't complain.

As of this morning the internal blower fan motor is running at full belt. I can change the temp and air direction no problem but it won't reduce speed on auto or by manually changing the speed with the + or - buttons (the number of green telltale lights increases and decreases but the speed stays on full).

Maybe a speed control has failed ?

Answers on a postcard please.

Almost certainly the power transistorsin the speed controller have failed. They are not too difficult to replace. Complete controller assemblies are available on Ebay, but there were a few of those which were not fit for purpose.

xantia_v6 wrote:Almost certainly the power transistorsin the speed controller have failed. They are not too difficult to replace. Complete controller assemblies are available on Ebay, but there were a few of those which were not fit for purpose.

Thanks for this, it makes perfect sense - I'm happy to replace the component if it's easy to identify. Is the speed controller situated behind the heater controls and do you have any diagrams/transistor numbers to hand ?

Having spent the past 5 hours fighting to get rusted bolts etc from the bumper so I could remove it to replace the drivers side headlamp glass (recently donated by a very generous forum member) and a smashed indicator glass courtesy of ebay I'd love a nice easy step by step guide how to fix the fan problem.

Yes, I know. I'm a lazy sod !

Fan motor is found under the dash in the passenger side foot well.
Some electrical plugs to uncouple then the fan is held in place by 3 screws.
There is a self help guide to transistor replacement on the other XM forum.
They are dead easy to repair once you have done your first one.
Lots of the transistor control modules (allegedly Citroen part 6441.78) on ebay but most are crap.
Spec error led to incorrect transistors being fitted to a very large copy batch of modules.
Might be worth asking on here for a known working XM fan or duff one to repair.
That way the in car swap becomes fast and simple.

John

The controller is in the base of the blower assembly,

see viewtopic.php?f=8&t=2929&start=30" onclick="window.open(this.href);return false;"
and viewtopic.php?f=8&t=6776" onclick="window.open(this.href);return false;
and http://www.frenchcarforum.co.uk/forum/v ... hp?t=25122" onclick="window.open(this.href);return false;
for some info

Thanks for all your replies, much appreciated.

The fault in my car is that the fans run full speed only after the engine has been started. I see that the fans shouldn't run unless the engine is running so this is partially correct.

I've seen various good/bad/ugly transistors on ebay but can also also get the following MJ11015G from RS Components (a branch is 5 miles from me so I may be able to collect today if they're in stock)

http://m.rs-online.com/h5/mobile/uk/cat ... 0854%7Calt" onclick="window.open(this.href);return false;

Do you think replacing the transistors will solve the problem and are the ones from RS correct ?

There is also a relay on the board, which I think shuts of the blower when the engine is not running, so I think your symptoms are normal for blown transistors.

Right, I've got new transistors and am removing the fan as we speak.

Two questions:-

1. How the bloody hell does the connector that connects to the PCB with the transistors on come off ?
2. Does the fan need to be removed to get the PCB out and if so, how ?

Feel silly but need to get this off and apart before it gets dark.
Ta

Got the fan off but the bloody PCB connector won't pull off. It looks like it should just pull off but if I pull it any harder it will probably break. Is it just stuck or is there a hidden catch somewhere ?

It's really infuriating !!!!!

Done it !

Took a pair of angled pliars and on "oh sod it" attitude but it's off.