2004 c5 hdi 110 cooling fan woes FIXED and now running (pg 6 on) .

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

Moderator: RichardW

citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

2004 c5 hdi 110 cooling fan woes FIXED and now running (pg 6 on) .

Post by citroenxm »

Hi all..

So.. Who can answer this... After getting the wiring diagrams etc I set out looking while sitting.. At the wireing to see why there's no life from the cooling fan..

Spent 2.5 hours checking every wire from the three relays and every single wire checked out with continuity.. No shorts.. No corrosion.. Everything checks out.. So checking the two pin plug to the fan there's 12v while the engine is running and AC is on. So plugged it in.. No fan.
So I thought fan fault. Took fan out and opened it up.. And surprised to see its a 4 brush motor..
DSC_0065.JPG
DSC_0068.JPG
Blew out the brush dust.. Springs on the brushes looked good.. So I put it back together.. Re assembled and put 12v directly to it from a battery.. And it spin up.. Cracked. It I thought.. Put it back on the car. Plugged it all up.. Started.. Ac on.. And yes ac does work.. And nothing.. No fan.. Still have 12v at the connecting plug... Took plug apart fed 12v to it from battery worked no problem....., could it be a plug. Problem? I even took the plugs off the two resisters and shorted them out with a cable. Still no fan... So.. Im at a complete loss. Its only thing stopping the sale. Other the needing a electro vaccum valve for the egr valve.
Last edited by citroenxm on 30 Jul 2021, 18:00, edited 3 times in total.
admiral51
Donor 2021
Posts: 2376
Joined: 24 May 2007, 10:11
x 300

Re: 2004 c5 hdi 110 cooling fan woes

Post by admiral51 »

Assuming the pins on the fan are male and the plug are female have you tried running a short length of cable between both pins of both fan and feed plug to see if there is a loss of voltage between the 2.
I cannot see why it would not kick in if it has 12v at the plug but then it could be a small fracture on one of the pins when pushing them together ?

Just thinking of something different to try that you can check the voltage between plug and fan in situ

Colin
MGmike
Posts: 96
Joined: 29 Aug 2020, 18:29
x 12

Re: 2004 c5 hdi 110 cooling fan woes

Post by MGmike »

Sounds like a relay contact problem.
Although you have 12v at the plug when disconnected for the fan, you are checking it with zero current flow. What you need to do is to check the voltage at the plug with the fan connected. Either by breaking in the the plug or as admiral51 says, by connecting bridge wires that allow access to the terminals.

My guess is the relay contacts are burnt and presenting a high resistance which causes a large voltage drop when current is required.
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

OK. I have pleanty of relays I can swap in and try..
admiral51
Donor 2021
Posts: 2376
Joined: 24 May 2007, 10:11
x 300

Re: 2004 c5 hdi 110 cooling fan woes

Post by admiral51 »

Ok another stupid question regarding cooling fans from me based purely on my knowledge of the Xantia 3 relay set up.

Is there a plug/sensor on the thermostat housing that reads temperature that if unplugged should put the relevant ECU into default mode ( no reading ) and put the fan on at full chat ?

Just thinking that if there is and the fan works in situ with it unplugged then maybe its an ECU controlled issue?

12v maybe should be present but the current required needs the relays to boost it to allow the fan to spin, direct 12v from the battery will provide the current also so maybe the relays are ok but they have not been told to wake up and get to work ?

Yes i know very little about electrics but just thinking of what to try etc

Colin
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

I could try that. Yes it's hdi 8v 110 with the single sensor on the side of the thermostat housing on the side of The engine...
User avatar
white exec
Moderating Team
Posts: 7378
Joined: 21 Dec 2015, 13:46
x 1443

Re: 2004 c5 hdi 110 cooling fan woes

Post by white exec »

One fan or two, Paul?
Swap out the relays with known good. Check whether one of them (maybe) is 5-pin, to match its 5-pin socket.

You can also substitute the fan(s) with a 55/60W headlamp bulb, to check slow-speed / high-speed running.
Pulling the brown temp sensor (with IGN on) usually triggers fast running immediately. Reset by re-connecting, and turning the IGN off then on.
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

Yes Chris. Single fan. Think all S1 c5 are single fan.
User avatar
white exec
Moderating Team
Posts: 7378
Joined: 21 Dec 2015, 13:46
x 1443

Re: 2004 c5 hdi 110 cooling fan woes

Post by white exec »

Single fan, so there must be a dropper resistance there somewhere, to provide slow speed.
Is the resistance and its connections ok?
It's slow speed that should happen when AC is switched on.

Pulling the temp sensor normally triggers high speed (a fail-safe mode).
Fan likely to be 100...150W, so use a couple of H1 bulbs in parallel (or an H4 both filaments) as substitute.

I don't have the wiring diagram here. Can you post it?
admiral51
Donor 2021
Posts: 2376
Joined: 24 May 2007, 10:11
x 300

Re: 2004 c5 hdi 110 cooling fan woes

Post by admiral51 »

Pull the stat plug before you change any relays

The A/C works without the fan running as in earlier post so does it need to be running or is it that we think it should be running with A/C on as in previous Citroen vehicles.

Colin
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

white exec wrote:
15 Jul 2021, 20:07
Single fan, so there must be a dropper resistance there somewhere, to provide slow speed.
Is the resistance and its connections ok?
It's slow speed that should happen when AC is switched on.

Pulling the temp sensor normally triggers high speed (a fail-safe mode).
Fan likely to be 100...150W, so use a couple of H1 bulbs in parallel (or an H4 both filaments) as substitute.

I don't have the wiring diagram here. Can you post it?
Yes. Here.
Screenshot_20210713-220845.png
User avatar
white exec
Moderating Team
Posts: 7378
Joined: 21 Dec 2015, 13:46
x 1443

Re: 2004 c5 hdi 110 cooling fan woes

Post by white exec »

Hi Paul,
That looks like a 3-speed fan set-up, using 3 relays and 2 dropper resistors.
I don't have a list of those components codes, so am just following the connections.
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

Fcf wiki page has got them.. 😉😉

That's where I got my key from..
MGmike
Posts: 96
Joined: 29 Aug 2020, 18:29
x 12

Re: 2004 c5 hdi 110 cooling fan woes

Post by MGmike »

I agree with Chris, it's a three speed fan determined by the relays and the dropper resistors.

1509 is a straight forward full speed controlled by the ECU when the coolant temp gets too high.
1508 is the slowest speed, again controlled by the ECU but probably when the a/c is on but it may actually be on all the time.
1548 is the stranger one as its controlled by the BSI, possibly when the a/c is on? However it gets it's main power feed from 1508 and therefore unless 1508 is activated it does nothing. That said, when both are activated they feed the motor via two resistors providing an intermediate speed.

I would concentrate on relay 1508 to start with... If you pull the relay and insert a bridge wire on 3 & 5 the fan should run at a low speed.
If it does... great you have a relay fault (note: is a special(ish) relay with a diode in to protect the ECU and must be replaced by one of the same type). If the motor doesn't run you need to check the wiring and resistor 1506. (let us know what the resistance measures at and we'll be able to work out what the operating voltage and current will be for each speed).

The big kicker here is you might still have a fan motor fault! You know the fan runs at full speed but you don't know what voltage is needed to run it at the lower speeds. Stiction in the motor could require more volts/amps to overcome than the resistor allows. To partly prove this, bridge pins 3 & 5 on both 1508 and 1514. Hopefully the motor will run but probably it won't be as fast as it should be.

If it runs you have two options
1, replace the fan
2, add another resistor in parallel with 1506 to overcome the stiction in the motor.

best of luck with it....
citroenxm
Posts: 7995
Joined: 31 Dec 2004, 00:10
x 49

Re: 2004 c5 hdi 110 cooling fan woes

Post by citroenxm »

Fantastic I'll give that a a go. That's great stuff..

Thankyou..