Dodgy blower fan cure

peteh · Post by **peteh** » Fri Sep 22, 2006 7:55 pm

My BX txd suffered the usual non working blower, managed to cure it, it may work for anybody with the same prob' remove all the control knobs 2 screws air vents etc and remove panel, undo the 4 screws that hold the heater controls, you will see behind the blower switch a multi plug, i simply bridged the 2 brown wires with another piece of wire and hey presto blower now working on all speeds, looking at plug they are the 2nd and third wires in from the right side of the plug, you never know it may be a simple cure for anyone else, more so with winter and steamy windscreens round the corner. I must be dead keen as i replaced all the dash and heater bulbs as well!! Just wish i had a glovebox lid, ciggie lighter, roof ariel, and a washer pipe for my wiper

tom · Post by **tom** » Sat Sep 23, 2006 8:05 am

All speeds? Take a look at other postings on this issue! The Earth problem is well known and the fix you suggest is ok, but the better approach is to run in a new earth to the control board because there are many series connections that tend to become counter conductive. Many BXs never run their fans at full speed due to a design fault. If your control board is marked ELEDASA, it needs to be modified. Plenty of info on this forum...

peteh · Post by **peteh** » Sat Sep 23, 2006 10:03 am

Thanks for advice Tom, my objective was to get some demisting capability, bonus is that all speeds are working fine, but may run a complete new earth through it at a later date

ianselva · Post by **ianselva** » Sat Sep 23, 2006 10:18 am

I have the same problem , can some one point me to the previous posts for the approved remedy.

Ian

jeremy · Post by **jeremy** » Sat Sep 23, 2006 10:56 am

This one'll keep you busy for hours.

I can vouch for the existance of the full speed realy and the need for the modification to the PCB.

http://www.frenchcarforum.co.uk/forum/v ... php?t=6133

ianselva · Post by **ianselva** » Sat Sep 23, 2006 12:56 pm

It already has , I gave up last year and put a seperate switch in the loom leading to the PCB, but I thought I'd have another try with help from this forum. The Blower works OK , the relay seems to test OK, Ive checked the moving contact on the PCB but the dashboard rhestat does nothing .
Now I'll go and try your suggestions.

Ian

ianselva · Post by **ianselva** » Sat Sep 23, 2006 3:10 pm

Great guys !
I've fixed it thanks to the tips on the forum . First time its worked from the dashboard in at least 2 years.

Ian

sleepy0905 · Post by **sleepy0905** » Sat Sep 23, 2006 5:56 pm

OOH OOH who has the info or picture for modding the blower PCB as my full speed relay dont work either.

tom · Post by **tom** » Sat Sep 23, 2006 8:27 pm

Pointers to the site have been posted here before. It may take a little effort and research to find them but they are definitely here.

sleepy0905 · Post by **sleepy0905** » Sat Sep 23, 2006 8:53 pm

Thanks jeremy for your link i couldnt find the info but i am dyslexic it was my wife read it and found the info.
Oh yes tom your attitude stinks I only asked because I have tried and failed in the past to find and do this mod but i at least now have the info thanks to jeremy.

tom · Post by **tom** » Sun Sep 24, 2006 11:23 am

Thank you Sleepy. As the originator of the mod, I read the posting from Jeremy in this thread.and found that the web page was listed on the link he gave. The topic is regularly covered and the link on here has been posted several times. Many people here have found and used it to their advantage. I would prefer an attitude that (to you) stinks to an attitude of I'm so lazy that I'll get somebody else to do all the work again despite its having been repeated ad nauseam for the past eighteen months. Knowing several people who are dyslexic, laziness is not one of the symptoms.

AndersDK · Post by **AndersDK** » Sun Sep 24, 2006 1:36 pm

Stop arguing like kids and read the facts :
http://www.frenchcarforum.co.uk/forum/v ... highlight=

Jaba · Post by **Jaba** » Mon Sep 25, 2006 7:37 am

I first did this mod in 2000, thanks to a guy called Duncan Myers. I didn't find it actually made a lot of difference though.
It was on an aircon car. There is a controlling microswitch on the temperature control knob. The circuit on these is such that the high speed relay only activates when the temperature control is set to cold.

So if you are using heating then Citroen designed the circuit so that the high speed relay was not used at all at full blower speed. If this was their intention for aircon cars - to only give true full speed when the aircon was in use to give the maximum blower force to cool the driver down or for demisting then perhaps it explains why it was not implemented on non aircon cars. Dunno why they bothered to fit the relay though.

All this is conjecture - we will never really know. What we can do though is do the mod and benefit from some more airflow on on all the single blower BXs.

jeremy · Post by **jeremy** » Mon Sep 25, 2006 6:48 pm

I think what has happened here is that Citroen wanted to use an apparently infinitely variable fan rather than the 3 or 4 speeds of the opposition. Variable resistors for motor loads are a rpoblem and tend to run very hot and so case all sorts of problems includuing where do you put the things so they don't burn the plastic trim etc.

Citroen solved this by using a carbon track resistor carrying a low current and transistors to amplify this current. This works nicely but on full power the transistors still have a noticeable resistance - so nice easy solution is simply to make the maximum speed position on the switch operate a relay to bypass the transistors.

As we now know the circuit boards were incorrectly manufacturered and thgings didn't work as planned - why did this take so long to discover - well I expect it was only when knowlegeable enthusiasts started to repair things that the problem was noticed.

There's no mention of the relay and bypass in the instruction book - its not common so a new owner wouldn't notice or complain - and probably everyone just thought the fan was a bit quiet and feeble - which is what I did till it stopped working at all and I had to investigate.

shavedchimp · Post by **shavedchimp** » Sun Oct 01, 2006 11:55 pm

The blower in my BX is not as powerful as it used to be - what may the problem? The heater is still working though.

Shavedchimp

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