Cooling fans not working

MikeT · Unread post by **MikeT** » 23 Dec 2008, 16:45

I know it's been well covered before, I've spent the last evening reading as much as I can but taking it all in wasn't possible (memory full or CRC failure I think

)

The problem is my fans won't come on to cool the radiator. The temeperature gauge works, as does the temeperature warning light (shown when the ignition is first turned on) but despite nervously watching the temperature climb to a scary 111 degrees, the fans remained motionless while neither the STOP light or the temp warning light illuminates.

It does have A/C but this was bypassed (2002 I think) because the compressor clutch had seized. If I remove the brown sensor connector on the thermostat housing while the engine is running, there's a 1-2 second delay then the N/S fan spins up full speed. Apart from at least one fan working, does that eliminate any other component from the tests I need to carry out?

admiral51 · Unread post by **admiral51** » 23 Dec 2008, 20:44

Hi Mike
Sorry to hear that you are having the dreaded fan problem

Im sure Clogzz will offer much more technical info than i can but ill put my tuppence worth in now

As you know both fans must operate together at both speeds so i would diagnose the problems as follows
1. Bitron sensor is working as it should otherwise fan would not work when sensor removed
2. As only one is working at full speed suspect relay to inop fan faulty as if ok working fan should run at both speeds
3. Switch over relay for full speed working
4. Non working fan may be faulty but should not stop working fan running at both speeds
5. As temp gauge working suspect contacts from sensor to bitron being at fault because as soon as sensor removed open circuit sets fan/fans at full speed or possibly sensor itself as i think one part sends signal to gauge other part to the bitron

As you know Mike im no expert but i reckon you may have found the cause of the original HG failure

If you find that the inop fan is dead then i do have a couple of spares that you are more than welcome to along with a bitron unit but these are all from a S1 not a S2 which i believe yours to be

Im sure others will be able to give more detail info im just going from amature fubblings

Colin

Unread post by **xantia_v6** » 23 Dec 2008, 21:08

Your first job is to get both fans running at high speed. If one fan doesn't run at high speed, then neither will run at low speed.

Start by checking the relays between the fans. These can fail, or can burn at the connectors. I have even had one that had just fallen out of its socket.

If the relays look OK, you can (with a bit more info than I have to hand) bridge the appropriate relay socket connections to run each fan, in order to check that the fan motors are OK.

Unread post by **CitroJim** » 23 Dec 2008, 21:14

Mike,

Here's the cooling circuits for the MK2..

Circuit

Harnesses

Locations

Hope they help Mike....

Apologies they're a bit on the tilt.. MK2 diagrams are printed on inferior paper compared to the MK1 ones and they don't lie so well on the scanner bed

MikeT · Unread post by **MikeT** » 24 Dec 2008, 12:34

I'll have to suspend this thread until xmas is over now. Thanks everyone and have a good holiday.

jgra1 · Unread post by **jgra1** » 24 Dec 2008, 12:46

have a good one Mike

John

MikeT · Unread post by **MikeT** » 08 Jan 2009, 15:55

I've been doing testing today and can confirm all three relays are good. I'm not sure which of the two green relays are left and right. One is on the right but the other is bottom centre with the switch over relay on the left.

I would be grateful if anyone could logically assess the data I've aquired so far. With the relays removed, I found the following pins showing +12V

Ignition OFF
R.H Relay Pin3
B.C. Relay Pin3

Ignition ON
R.H. Relay Pin3 & Pin1
B.C. Relay Pin3
L.H. Relay Pin1

Ignition ON and Temp Sender disconnected
R.H. Relay Pin3 & Pin1
B.C. Relay Pin3
L.H. Relay Pin1

...which has confused me even more. I'll try and decipher the wiring diagrams given (thank you) to see what each pin connects to, though from the relay diagrams I can see that Pin3 is the high current IN feed with pin5 being the high current OUT feed. Pins 1 & 2 being the on/off switch.

Off to study the diagrams now, I may be some time

KevMayer · Unread post by **KevMayer** » 08 Jan 2009, 19:23

Looking at the circuit diagram pin number 1 of the BC relay should be live with the ignition on or off. That's assuming the BC relay is the one numbered 1502 in the wiring diagram.

The +ve to pin 1 of the BC relay is supplied by fuse F14 in the BF00 unit.

Fuse F14 needs to be checked.

It looks like one of the fans (1511) could run on fast speed if F14 has popped but that depends on whether the control unit 8010 will work if fuse F14 is no good. So, when you pull the brown sensor and only one fan runs at high speed that points at F14 being popped.

Basically the two fans are connected in series to run together on slow speed and then are connected in parallel to both run on high speed.

Good luck.

Unread post by **RichardW** » 08 Jan 2009, 20:58

Mike,

Doesn't look quite right there somewhere...

You should have:

Ign off:

12V on pin 3 of both the fan relays;
12V on pin 1 of one of the fan relays (1502) - the bitron must switch the earth side of the relays to activate them.
Pin 5 on the change over relay should be continous to earth.

Ign on:

As above, but you should now have 12 V on pin 1 on all relays

Sensor dis-connected:

As you have seen there is no difference between the 12V on the pins - the Bitron will earth pin 2 on all the relays, so you should be able to measure continuity to earth on these pins.

You are missing the 12V feed to pin 1 on 1502 by the looks of it. This comes via F14 as Kev suggets and is the first place the look.

MikeT · Unread post by **MikeT** » 08 Jan 2009, 23:23

KevMayer; Thanks for confirming the Left Fan Relay(1502)Pin1 should be live, that's about all I managed to figure out. Yes, to confuse me more, on this Xantia the Switch Over Relay (1504) is positioned where the Left Fan Relay(1502) is shown on the harness diag Jim supplied. And even the handbook is conspiring against me - it states fuse 14 is 5A for "Injection ECU - Refrigeration Cut-Off Relay" I'll check them anyway as my handbook also says Engine Bay Fuse 3 is 30A for "Cooling Fan" & Fuse 5 is 5A for "Cooling fan". Thanks again Kev.

RichardW; As above and I confirm I hadn't traced any earths, just looked for +ve signals. I'll learn!! Thanks. Looking promising on finding the culprit. I might even find time to short the pins that should fire the left fan.

Clogzz · Unread post by **Clogzz** » 09 Jan 2009, 13:23

Shorting pins 3 & 5 of 1502 will spin both fans at the low speed.
That’s 30 & 87 on the relay.

It does look like there’s a run of cars with the relays in strange places.
This violet one is the change-over relay.

MikeT · Unread post by **MikeT** » 09 Jan 2009, 14:07

Thanks Clogzz, I assume that should work while the other realys are still removed? Incidentally, my relays are marked pins1-5 as well as the connector socket (not that it makes any difference).

That's how mine are located only the violet one is black.

Clogzz · Unread post by **Clogzz** » 09 Jan 2009, 14:47

It won’t work without the change-over relay in because the current for low speed passes through pins 3 & 4 of the change-over relay.
This contact is closed with the relay at rest, and is open when energised for the high speed.

I’ve got a black 5-pin relay here, instead of it being in its place in the car.

It also has the pin numbering from 1 to 5, and a black-on-black diagram on the side, showing pins 3 & 4 closed when not energised.

The black relay, of ‘Cartier’ brand, is an original Citroën fitment, and says 25 Amps above the side diagram.
For its 25 Amps, it’s heavier than some no-name relays that claim 40 Amps.

My car only has relay 1502 in it, from when I was fiddling to find the cause of unnecessarily going to high speed.
That’s fixed now, and the other two relays will go back in when I can make time for that.

The picture shows the usual arrangement with 1502 at top right, and a piece of wire acting as pins 3 & 4 of the change-over relay.

MikeT · Unread post by **MikeT** » 09 Jan 2009, 17:50

Clogzz wrote:It won’t work without the change-over relay in because the current for low speed passes through pins 3 & 4 of the change-over relay.

Ok, will replace the COR before I try. Alternatively, could I also jumper 3&4 instead?

Clogzz wrote:I’ve got a black 5-pin relay here...It also has the pin numbering from 1 to 5, and a black-on-black diagram on the side, showing pins 3 & 4 closed when not energised.

That's exactly what I have/was fitted as the COR

Clogzz wrote:The black relay, of ‘Cartier’ brand, is an original Citroën fitment, and says 25 Amps above the side diagram.

Ditto, as are the two green fan relays I have.

Clogzz wrote:The picture shows the usual arrangement with 1502 at top right

This initially confused me as the pic shows your 1502 as the Black relay which I'm calling the COR but I suppose it doesn't matter as it'll operate the same.

It's all good learning experiences. Thanks and I'll report back my findings when I've tried all the suggestions made.

Clogzz · Unread post by **Clogzz** » 10 Jan 2009, 13:23

Yes, you can jumper pins 3 & 4 of the change-over socket.
That’s how mine is working now, but it’s not too obvious from the picture with the black jumper wire.

If all the relays have 5 pins, they can be changed all around.
All that matters is that the change-over relay socket with 5 terminals gets a 5-pin relay put into it.

Enjoy a good fiddle.