Xantia Blower - FINALLY FIXED!!!

Post by **Peter.N.** » 06 Apr 2010, 01:12

Hi David

I did have one to bits and fault find it once, but that turned out to be the motor! There are several chips on the board which doesn't exactly help diagnosis, I thnk you would be better off with a secondhand panel.

Peter

Post by **CitroJim** » 06 Apr 2010, 06:12

Peter.N. wrote:
DHallworth wrote:OK....

On the orange cable (thin one) going into the fan multi-plug there is less then 0.1 of a volt.

David.
That will be your problem then, if I remember correctly there should be around 3 volts on this wire, its the control signal from heater panel, if you connect it to 12 v the fan should run, sounds as though the fault is in the control panel

Peter

If this is the wire going to pin 3 of the brown plug then +12v here will stop the fan whereas an earth will make the fan run at full speed.

Don't be confused by trying to measure a voltage at pin 1. This is just a thermistor measuring heatsink temperature on the regulator. It signals the ECU to make small changes in speed to compensate for heating effects.

Here's a diagram of the blower regulator.

Post by **Peter.N.** » 06 Apr 2010, 09:58

Sorry Jim, forgot they were PNP transistors

Post by **CitroJim** » 06 Apr 2010, 10:13

Peter.N. wrote:Sorry Jim, forgot they were PNP transistors

No worries Peter. I've alwas had trouble with PNP transistors; possibly as there was never really a PNP concept in the days of valves

Whenever I look at a circuit diagram containing transistors I mentally relace them all with triodes. I can then understand better how they work....

Just imagine if the blower regulator did have valves in it... No need of a heater matrix for sure....

Post by **DHallworth** » 06 Apr 2010, 10:40

Well I'm going to have another go at this tonight.

I'm getting really fed up with this thing now.

I'm on the verge of calling in an auto electrician. If I could of repalced it easily with another HDi Exclusive this one would be broken by now.

David.

Post by **DHallworth** » 07 Apr 2010, 13:12

Righto....

On the brown plug that goes onto the blower:

Between the thick red and black pins (supply and negative) there is a solid 14.4v with the engine running.

On the two thin cables, the orange and white ones:

Orange cable to earth: 0.4 volts
White cable to earth: 4.4 volts

Orange cable to white cable: 4.4 volts.

If I bypass the the motor control circuitry the fan comes on at full speed.... I unplugged the red cable going into the motor and the black cable going into the motor, then made a short patch lead to go from the brown plug to the plugs on the motor and it came on at full speed.

I think the fault is on the control circuitry. I tried the ECU (Rectangular valeo box that sits in footwell) from my Activa which I know works an this made no difference.

I have no idea where to go from here now!

David.

Dommo · Post by **Dommo** » 07 Apr 2010, 14:23

Is it worth trying a new set of sliders? The things you adjust to make the fans work and what not. I can't remember if all the adjustments are cables pulling on things, I seem to remember one of them having an electric part on but can't be sure unfortunatly so if I'm way off I apologise!

Post by **DHallworth** » 07 Apr 2010, 15:17

I'm tempted not to think it's the slider as when I shorted it out the slider was working ok.

I'm at a total loss with this one.

David.

Post by **Peter.N.** » 07 Apr 2010, 19:25

If the control unit is working properly, varying the speed control should result in the voltage changing on one of those thin leads.

Peter

Post by **DHallworth** » 12 Apr 2010, 13:13

Well this has got me completely baffled now.

I've got 12v getting to the air con ECU but no signal coming from the ECU to the thin wire that goes into the fan.

When i scan the car with the Lexia it can talk to every ECU apart from the Air Con ECU. I've tried the Activas one which I know works and it's not changed anything.

When I plug the fan in it gives an initial kick but nothing else, this is the same on 2 fan units.

If I short out the fan by plugging it into the feed on the brown plug directly it comes on at full pelt.

For some reason though as soon as I plug it in properly it does nothing.

If anyone locally understands these things and wants to earn some beer tokens I'd greatly appreciate a 2nd opinion!

David.

Clogzz · Post by **Clogzz** » 12 Apr 2010, 14:16

If the fan gives an initial kick, it may be a case of the fan not being able to spin at low speeds.
Slider faults cause a permanent second speed.
Slightly worn motors will run at full voltage, but may not run at reduced voltages for low speeds.

Maybe some ideas here:
http://www.frenchcarforum.co.uk/forum/v ... hp?t=23767

Post by **Peter.N.** » 12 Apr 2010, 21:12

I had a similar problem on one of my XMs, cured by replacing the panel with a secondhand one.

Peter

Post by **DHallworth** » 15 Apr 2010, 23:57

Right....

I went out to the car today and plugged the brown into the fan.

It came on at full speed for around 5 seconds and then went off. It did this with the control wire plugged in and unplugged.

I tried it on a spare motor and it did exactly the same.

After 5 seconds have passed the motor stops dead. The only way I can get it to come back on is to unplug the brown cable for a few seconds and then plug it back in again.

Anybody got any ideas? I'm hoping this is the light at the end of the tunnel.

David.

Post by **CitroJim** » 16 Apr 2010, 12:44

David,

This is odd.

Do you have access to an oscilloscope, either of the real kind or of the type built into a Lexia?

I'm intrigued to see precisely what is going on on the speed control libe to the regulator when this problem is apparant.

Post by **DHallworth** » 16 Apr 2010, 12:51

Hi Jim,

I've got a Lexia.

Problem is it can't talk to the Air Con ECU for some reason.

Talks to everything else on the car with no problems at all!

David.