Xantia Air cond diagrams and Fan problem

juraj · Post by **juraj** » 10 Mar 2008, 10:45

Hi all

my first post here ....

My xantia - 1997 with air conditioning - fan no longer works, i suspect the transistor board as the plug has power, however interestingly the two thick leads, the red supply and the black earth have both got very hot in the past as they have started to melt the plastic of the plug. Which suggests another problem as well, perhaps the motor was drawing too much current, so the red line was getting hot, by the earth line to be hot as well? Perhaps there is a poor earth offering some resistance so its heating up as well,

Also the Haynes manual has a diagram in it for the fan circuit, it simply does not show the transistors and the fan apparently gets just one wire to it from the control, which is obviously incorrect, so my question is does anyone know what the two signal lines to the fan should be at various control switch positions. As I have tried measuring the voltages at these signal lines at various control switch positions and the readings do not make much sense and weren't very consistent.

I am going to try a new transistor board or replace with new transistors,

But my other problem is that the air conditioning is not working. The switch does not light up and there is never any power to energize the clutch in the compressor, however the thermostat fan is always on regardless of air conditioning switch or heater control lever position or fan switch position.

Haynes manual has nothing at all on the air conditioning components their location or even a wiring diagram, does anyone have a air cond wiring diagram? Does anyone know where the thermostat fan is? I want to disable it for the time being.

Also in a correctly functioning system when should the thermostat fan be switching on?

bye all

j

Post by **RichardW** » 10 Mar 2008, 12:12

There are myriad threads on Xantia heater blowers. Try this one for a good starter

Fan troubles

The A/C won't work if there is no gas in it - have you checked this?

Not sure what you mean by 'termostat' fan? If you are referring to the small one in the dashboard behind the alarm LED then this should run all the time - the climate control will attempt to regulate the temp in the car regardless of whether the A/C is on or not.

Clogzz · Post by **Clogzz** » 10 Mar 2008, 12:28

Hi juraj, and welcome to our ‘educational’ playpen.

And thanks, Richard, I wrote this before I saw your post.

---------------------------------------------------------------------------------------------------------------

The thick red and black plugs are melting the plastic because they’re loose, and have caused the fan to stop by now.
The current is very high there, 15 to 20 Amps, and the plugs need tightening.
The current originally goes through the ignition switch, until that packs up, and a relay gets plumbed in to take the current off the ignition switch.

The transistors aren’t faulty, their habit is to go short-circuit, and cause the fan to spin flat-out all the time.

With the air conditioning off, the engine cooling fans shouldn’t turn when the engine is cold or cool.
Turning the air conditioning on must always turn on both fans at the low speed, and stay on for all the time that the aircon switch is on, irrespective of whether the compressor has clutched in.

The high fan speed is an emergency situation like engine overheat or overpressure in the air conditioning.

Both fans always have to do the same … both stopped, both at high speed, or both at low speed.

I’ll be back with more later or tomorrow, it’s getting late here, and I trust that other members in the know won’t be far behind.

Here are a few links for perusal until then:

http://www.peugeotlogic.com/workshop/ws ... fanop1.htm

From RichardW: http://www.geocities.com/tricky992002/fanmod.xls

http://www.aussiefrogs.com/forum/showth ... 179&page=2

http://s132.photobucket.com/albums/q23/Clogzz/

http://www.frenchcarforum.co.uk/forum/v ... hp?t=22348

http://www.frenchcarforum.co.uk/forum/v ... hp?t=21372

juraj · Post by **juraj** » 10 Mar 2008, 14:32

hi guys thanks so far,

richard, yep ive read a lot of them, as for 'The A/C won't work if there is no gas in it - have you checked this?', well regardless of how charged the system is it wont work if the clutch in the compressor is not being energised,

'If you are referring to the small one in the dashboard behind the alarm LED then this should run all the time' - yep thats the one, but surely if the fan switch is set to off the climate control should but out, as the little fan is relaitvely noisy and is quite annoying and if for insatnce its cold and you set the heat control lever to full heat whats the point of climate control trying to regulate things?

Clogzz -

hmmm maybe they are melting it due to being loose, that would poin to a high resistance connection, but the plug actually takes a decent effort to plug in and out thus i doubt they are loose, also there is one more solitary thin line connector connected to the earth line, it is not normally earthed, but some system earths it at times i guess - air conditioning? - anyway when this is earthed manually by me the fan runs at full speed. Also putting in a replacemnt transistor board makes the fans run at low speed all the time, regardless of control switch position, thus im assuming the replacemnt board is faulty too.

'Turning the air conditioning on must always turn on both fans at the low speed, and stay on for all the time that the aircon switch is on, irrespective of whether the compressor has clutched in' - nope pressing the a/c switch doesnt do that, so I think that switch is faulty too as the inbuilt light does not light up as well,

this is why id like a circuit diag of the a/c system - then perhpas id see from it that the fans should run when it is switched on

bye all and thanks for the advice

Post by **RichardW** » 10 Mar 2008, 16:56

"well regardless of how charged the system is it wont work if the clutch in the compressor is not being energised, "

True, but there's a pressure swtich on it, and if the pressure is low it will not try and engage the compressor - I don't know though if it will inhibit the system to the extent that not even the light will come on. Perhaps you could take the switch out and see if you have 12V on any of the pins?

"yep thats the one, but surely if the fan switch is set to off the climate control should but out, as the little fan is relaitvely noisy "

Ahhhh - the fans runs all the time the ignition is on. It's not supposed to be noisy of course.... If it's noisy, then it's probably getting near end of life. You might be able to quieten it down by lubricating it, but I suspect it will eventually stop going round... stops it making a noise, but means the heating stops working

The fault with the blower sounds a bit like one we have not had before! How many more variations on a theme are there on Xantia blowers

juraj · Post by **juraj** » 10 Mar 2008, 17:30

hi richard

well that would explain the a/c comp clutch not being energised if there the pressure switch is senesing lack of pressure, again bloody haynes should have provided an a/c system diagram!

as for the little fan, where abouts is it? how do i get to it? i wanna give the lubrication a go, but the car has 105Kmiles on it - hardly excessive so the fan ought to have mor elife in it, but since its my first time in an a/c xantia i dont have anything to compare it by,

ive read most of the heater fan motor threads and i think mine is suffering from failed transistors, makes sense, one board made the fan run at all times in slow and the other wouldnt run it all,

i like citroens cos of the hydraulics but when will they sort out the electrics?!?!?!?!? my old cx - 1980 - was so poor in the wiring, most of which looked ot was done in the 1920-30s, there were few multiplugs mostly just single connectors, shocking stuff

MikeT · Post by **MikeT** » 10 Mar 2008, 18:00

Hi J,

Don't mistake a dim light for no light as I did. I eventually discovered that heat blackens the plastic diffuser reducing the emitted light severely.

The fan behind the led can be popped out as one unit (LED, temp sensor and fan motor) but it's quite long and may require a few leads to be unclipped. Removing the radio and/or clock should give good access.

juraj · Post by **juraj** » 10 Mar 2008, 18:07

thanks MikeT

actually i was not sure if the light is incredibly weak or severely dim, but i thought that at night it made the slightest difference when pressed,

also is the LED part of the sensor, ie is it actually there for a usefull purpose with regard to the climate control? or is it part of the car alarm circuit?

MikeT · Post by **MikeT** » 10 Mar 2008, 18:28

juraj wrote: is the LED part of the sensor, ie is it actually there for a usefull purpose with regard to the climate control? or is it part of the car alarm circuit?

Citroen simply utilised the little grill space by putting the LED for the alarm there. It's one complete unit that comes out with wiring and two plugs. If you break it down further, removing the LED with grill, you get this...

The A/C switch pops out and dismantles just as easily but, again, I found access via the radio compartment was necessary to re-fit the plug but I have large-ish hands.

juraj · Post by **juraj** » 10 Mar 2008, 18:32

thanks mike

is the fan tiny and in the picture somewhere or is this just the housing for the LED?

MikeT · Post by **MikeT** » 10 Mar 2008, 18:36

It's a poor example, sorry. The LED is not there. You see the casing on the left and out of range on that little stick is the thermistor (temp sensor). The fan blade is the lower part of the motor which is identified by the coil. When assembled, that is securely pushed into the LED grill (not shown) to hold it in place.

Post by **admiral51** » 10 Mar 2008, 19:17

Hi juraj
i dont have an A/C diagram but this may help in some way

To get the A/C clutch to energise the following must happen
1.engine running 2.temp must be +4 degrees C 3. A/C button switched on 4. interior blower must be switched on 5. both cooling fans must be running slow speed 6. High/Low pressure switch must complete to energise clutch.

The HP/LP switch is screwed into the side of the reciever/dryer which has the sight glass on.this switch has 4 wires running to it(on mine anyway

) 2 thick 2 thin.
If you unplug the plug that goes to the switch you can bridge the corrosponding wires to see if the clutch energises. From memory the thin wires if bridged should set the cooling fans both running at full tilt the thick wires when bridged should energise the A/C clutch
the above will only work if the steps 1-5 are ok

if you do get the clutch to energise then only run for a couple of secs so as not to damage anything the switch may not be faulty

i think there may be a short delay approx5 secs before the clutch kicks in once wires are bridged

the cooling fans must run together when they are on ie both slow or both full in the A/C set up the HP switch will set both fans to high speed as a default/safety measure .
you say they run full speed/slow speed when engine on i suspect you may have a dirty plug dodgy connection giving false readings to the bitron unit i dont think that is faulty as its doing what it should from info supplied to it

on the thermostat housing you should find the plug with the 2 wirs coming off it which gives the temp sensor for the bitron unit
by unplugging this with engine on should set fans at full speed ie overheating mode

.
if these connections are not clean it will give the bitron false readings. also the wires from the plug drop down and they could have a small break in them worth giving them a check.these wires run into n/s wing a brown plug i think

and again this can also give the same symptoms

hope this makes some sort of sense
try looking at this may be something similar or not

http://www.frenchcarforum.co.uk/forum/v ... m+overhaet

colin

juraj · Post by **juraj** » 11 Mar 2008, 00:40

thanks for elaborating mike

colin thanks too - just a quick question am running late to the arport - argh

point 4 blower must be switched on, i assume the 'auto' setting counts as switched on, also should the heating lever be to full left? or can it be anywhere or anywhere except full right - ie max heating

also where is the bitron control unit? (or computer?) what does it look like roughly? size? etc?

thanks for all the hlp will check it out further on weekend,

ps i dont think i have problem with the cooling fans on the front - my fan problem is with the interior heater blower fan

bye all - thanks again

Clogzz · Post by **Clogzz** » 11 Mar 2008, 11:22

Here for air conditioning maps, with more relevant pictures in this bucket:

http://s132.photobucket.com/albums/q23/Clogzz/

[edited]

juraj · Post by **juraj** » 11 Mar 2008, 11:30

thanks clogzz

the air cond diagrams will come in handy but those heating diagrams are in haynes too, you can see that the early and late versions are almost identical, component 8046 is the resistor pack in the early system, the later system has the transistor set up,

also where is the bitron computer?

bye