My turn for a C5!

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 12 Dec 2017, 23:16

She has the dual zone system. I do get the fan indicator, and then it goes out. I have checked (what I believe to be) the heavy duty connector to the fan, and that appears to be OK (no signs of heat damage). How easy is it to access that control unit?

I have (I think) found it. Myglaren posted up pictures in the following thread;

https://www.frenchcarforum.co.uk/forum/ ... hp?t=37936

User avatar
daviemck2006
Donor 2016
Posts: 4617
Joined: 04 Dec 2010, 19:45
x 252

Re: My turn for a C5!

Post by daviemck2006 » 13 Dec 2017, 00:47

Thats exactly what happened to my 1st c5, it was a 2.2sx with dual zone auto air con. The fan stopped working, but the heat still worked but had to be doing about 60mph to get any throughflow. That was one of the reasons I joined this forum all those years ago. Changing the module down beside the clutch pedal cured it.

Gibbo2286
Posts: 3000
Joined: 08 Jun 2011, 18:04
x 319

Re: My turn for a C5!

Post by Gibbo2286 » 13 Dec 2017, 00:52

Hell Razor5543 wrote:
12 Dec 2017, 23:16
She has the dual zone system. I do get the fan indicator, and then it goes out. I have checked (what I believe to be) the heavy duty connector to the fan, and that appears to be OK (no signs of heat damage). How easy is it to access that control unit?

I have (I think) found it. Myglaren posted up pictures in the following thread;

https://www.frenchcarforum.co.uk/forum/ ... hp?t=37936


If you go for that James check to see what's fitted before you order the new bit, mine was entirely different to the regular item shown in that thread. also check carefully around the fuse box under the bonnet, mine was corroded and melted away, that was the cause of my fan failure.

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 13 Dec 2017, 07:46

I will check the module, just in case, but can you let me know which fuse it is (and the value)? I assume it is one of the maxi fuses, as there is no mention of a blower fuse in the handbook?

User avatar
myglaren
Forum Admin Team
Posts: 14628
Joined: 02 Mar 2008, 14:30
x 331

Re: My turn for a C5!

Post by myglaren » 13 Dec 2017, 08:20

Mine would show the fan indicator for a few seconds then it would disappear.
This seems to be the indicator that the control module has failed.
If you replace it, there are numerous options on eBay at sensible prices, my last one was £20 and is still working. This will be my third one, second on the current car.

I have a theory that when the fans run full-tilt they draw too much current for the module to take and it burns out the transistors. Which is probably why they fail at this time of year.
Now, whenever the fan comes on full I manually reduce the speed a couple of steps.
I have a digital voltmeter plugged in to the fag lighter socket and both that and the one in the instrument binnacle show a significant voltage drop with fan on full.

Can't say with respect to a maxi-fuse as I have never had to look that far but one of Clogzz posts has a photo and legend for the maxi fuses.
Leaving for work now but will see if I can find it this evening.

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 13 Dec 2017, 08:23

Thanks for that, Steve.

Gibbo2286
Posts: 3000
Joined: 08 Jun 2011, 18:04
x 319

Re: My turn for a C5!

Post by Gibbo2286 » 13 Dec 2017, 11:40

Take a look at this thread, scroll down and you will find pictures of what I found on mine (an 04 C5 VTR)

viewtopic.php?f=3&t=58032&hilit=Heater+fan&start=15

User avatar
myglaren
Forum Admin Team
Posts: 14628
Joined: 02 Mar 2008, 14:30
x 331

Re: My turn for a C5!

Post by myglaren » 13 Dec 2017, 20:50

Pictures and description of the Maxi-fusebox here Jmes.
Doesn't look as though there is one for the heater blower though.

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 13 Dec 2017, 22:02

I found, in the engine bay fusebox (normal area, not the maxi fuse area), one 40amp fuse dedicated specifically to the heater blower. On my C5 this fuse is good (drat it!).
Last edited by Hell Razor5543 on 14 Dec 2017, 15:42, edited 1 time in total.

User avatar
CitroJim
A very naughty boy
Posts: 41167
Joined: 30 Apr 2005, 23:33
x 965

Re: My turn for a C5!

Post by CitroJim » 14 Dec 2017, 06:46

James, I have replied to your email ;)

Gibbo2286
Posts: 3000
Joined: 08 Jun 2011, 18:04
x 319

Re: My turn for a C5!

Post by Gibbo2286 » 14 Dec 2017, 11:16

Hell Razor5543 wrote:
13 Dec 2017, 22:02
I found, in the engine bay fusebox, one 40amp fuse dedicated specifically to the heater blower. On my C5 this fuse is good (drat it!).


James, I was thinking last night (in bed, things that pop up in your head) when I got the wrong part for mine it never went back because the seller wanted it returned to China but Paypal refunded the payment anyway so it's sitting here on top of my filing cabinet still in the box it came in.

PM me your address and I'll pop it in the post free gratis if you need it.

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 14 Dec 2017, 15:03

I have just yesterday ordered one from China (with an ETA between 27/12 and 12/01), so I will take you up on that offer (so I can get her warmer sooner). I will then retain the new one for the same purpose (in case anybody needs one) if that is OK with you?

If anybody has had a module fail, and the wiring has not taken this failure well, there are also suppliers who do a loom repair kit. They cost around £15. Here is one such kit;

https://www.ebay.co.uk/itm/2-Plugs-Wiri ... 1438.l2649

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 17 Dec 2017, 17:46

I believe that I may have found the fault with my blower control module. There are no signs of scorching, but a few of the solder joins are very poor. I will try to re-solder them, and update with the results.

Update: I now have a working blower module. There were a couple of failed solder joins on the connectors, including one that had a nice empty ring around it. I have introduced them to a soldering iron, and that seems to have resolved the issue. I would want to have another go with a better soldering iron when I can, but for now I have controllable wormth in the car.

Jim, the module looks nothing like the images I have seen for the Xantia 'resistor' pack. There are two seperate connectors. The larger one has four wires, two of which are the control wires (and are thin) and the other pair are the ones for the motor (and are heavy duty). The other connector is the output side, with a pair of heavy duty wires. The board has several surface mounted connectors (inluding a little IC), and there is one heavy duty component that is leaning on that massive heat sink. I will send you one of the new modules when they arrive.
Last edited by Hell Razor5543 on 17 Dec 2017, 18:14, edited 1 time in total.

User avatar
CitroJim
A very naughty boy
Posts: 41167
Joined: 30 Apr 2005, 23:33
x 965

Re: My turn for a C5!

Post by CitroJim » 17 Dec 2017, 17:54

Hell Razor5543 wrote:
17 Dec 2017, 17:46
I believe that I may have found the fault with my blower control module. There are no signs of scorching, but a few of the solder joins are very poor. I will try to re-solder them, and update with the results.


Fingers crossed James [-o<

Hell Razor5543
NOT Alistair or Simon
Posts: 8357
Joined: 01 Apr 2012, 09:47
x 489

Re: My turn for a C5!

Post by Hell Razor5543 » 17 Dec 2017, 22:58

Well, that seems to be working reasonably well. I do have a working blower, but the speed is not greatly controlled. Although there are no signs of scorching I wonder if I may have cooked something. I will fit one of the new ones when it arrives, to see what improvement there is.

There is one solder join I cannot manage (although it looks OK). This is the middle pin of what looks like a large transistor. This leg is also on contact with that very big heat-sink, so it is no surprise that my soldering iron cannot provide sufficient heat. It is not possible to remove the heat-sink, as it has been attached to the circuit board (this has three holes through it at the heat-sink end, and the heat-sink has been 'squeezed' at these points).