cooling fan switch/senser.(sussed out now?)

[dieseldoggy]

Hi all just got my doggy back with another engine in.but have problem with fans.ie don't work if you leave brown plug on senser/switch on fuel filter housing.do they work on a reverse circuit ie cold shut and hot open so broken etc as taken it off and fan stays on all time now.Cheers all

[Clogzz]

Wa-wa ?

It’s normal for the fans to spin fast with the brown sensor disconnected.
They will go to low speed when the engine is getting hot, like stuck in traffic.
High fan speed with engine running is overheat, and the engine should be stopped.
We have plenty of topics on the subject, because the fan control is a very common problem.

[dieseldoggy]

Hi yes found out some its. but what it was mech who put engine in had temp upto about100 and didn't think it was working/didn't hear fans.so disconnected it.i said it norm comes on about/just above normally? so reconnected now but will keep eye onit then sort out when see my mate to set up pump etc with computer as me cold starts/vacs not working atmo.
Ooh the joy's of a car! but many thanks for replying.

[admiral51]

Just a bit of info you may have missed

As you rightly say the fans will come on full speed with the sensor disconnected but in my experience the fans in normal operation should kick in on slow speed at or around 90 degrees.
When you disconnect the sensor both fans should run at slow speed for a few seconds before going to full speed.If not you could have a dodgy relay/connection but im sure Clogzz will be able to point you in the direction which relays control what

Colin

[dieseldoggy]

Hi yes i never realy heard the fans when running before unless outside.it never went over 100/3/4.but will be having a in depth look today!ooher! next week it's going to have cold start/tps etc done he will hook upto bosch pc thingey. will get him to check some of the settings etc.what i was wondering is it like/sim to fords when you switch circuit it grounds out which closes relays.anyway cheers guy's.i'l check back with you later.

[Clogzz]

Yes, the relays get grounded to close them.
Relay 1500A gets a permanent, non-switched supply, and is grounded to spin both fans at low speed.
Relays 1500B and 1500C have a key-switched supply, and are grounded to go to high speed, while 1500A also stays closed at high speed.
At high speed, all 3 relays are closed.

And thanks to Colin for the reference.

[dieseldoggy]

Had a poke at this yesterday clogzz. dont have any returns off relays by fans as had volts on one side but other side put meter to earth and had nothing.been through all the fuses etc what he said over the phone.has they dont work now with brown plug off either.changed bitron box over.after putting grill etc back now rev counters not working either.

[Clogzz]

The returns are earthed through the Bitron when the fans are meant to spin.
That’s not measurable until the Bitron switches them on.

1500A’s pin 2 is earthed through Bitron pin 1 for low speed.
1500B’s and 1500C’s pins 2 are earthed through Bitron pin 10 for high speed, with 1500A also staying earthed for the high speed.
Bitron pin 4 must have a permanent 12 volts, even with the key out.
Bitron pin 15 has 12 volts when the key is set to ignition.

You could try earthing the relay pins 2 with pieces of wire to see what they’re making of it.
Low speed will work even with the key out.
High speed can only work with the key set to ignition position.

The rev counter fault is unrelated, unless it has a common fuse.
Don’t know much about that, except that there must be a rev pick-up plug somewhere high up on the bell housing.

Enjoy a good fiddle.

[dieseldoggy]

Hi yes did have a good fiddle got soaked?.ha ha found out what problem was it's the fan units nearside works if you tap it now? offside go's very slooooow if at all.and rev counter was contacts on ECU.gave it a dosing of contact cleaner and now works.so now need to get pair of fans! are they the same or low&high speed?.Then the bigger job is getting front off to do that was no fun trying today gave up will do once got some fans. cheers matey and a gud day to yer blue.

[Clogzz]

Nice to see you progressing so fast.

The nearside fan is faulty, preventing the offside to run at low speed because at low speed they’re in series with 6 volts each.
The nearside usually packs up first because it’s on the grotty side of the road.
Both fans are the same, and they always have to do the same speed; both spinning at low speed, or both at high speed.
There isn’t a low speed fan, or a high speed one.

Now that you’ve got this far, unplugging the brown sensor may tell you if the fans will spin at high speed, which they can, even if one fan won’t spin at low speed, because at high speed they’re both fed 12 volts.

I’ll also try digging up a picture of the condenser and radiator unclipped from the top to improve access to the back of the fan motors.
I’ll post it in your other topic if I find it.

Keep enjoying plenty of very good fiddles.

[bosrasham123]

hi could u tell me were the cooling fan switch is on a 2006 Citroen c5 2.0 hdi vtr

[GiveMeABreak]

hi could u tell me were the cooling fan switch is on a 2006 Citroen c5 2.0 hdi vtr

You've asked this question already in another post - please don't multiple-post the same question - it confuses people when responding - I've asked you for information on the other post here:
http://www.frenchcarforum.co.uk/forum/v ... 45#p501494
so will respond on that post.