306 coolant fan control - advice please ?

Hi folks,
I've got a late model 306 with Air Con.
The two cooling fans are not cutting in when the engine gets hot in traffic,
although they do both run when the air con is switched on.
I've found 3 relays near the radiator that appear to control the fans, and
they all test OK.
Has anyone experience of the wiring of the fans, or what controls them ?
Many thanks,

- Steve

 

I did have the same problem with my Citroen Xsara, which is technically
the same like the 306. The 3 relays near the radiator were ok.
Did you check the main fuses? It is a box under the bonnet, near the
battery. In my xsara, this main fuse was blowing up every few days.
The citroen dealer replaced a hose of the aircon, after that it was solved.
He didn't tell me what it really was.

 

<snip>

Hiya VTR16V,
That's very interesting. It sounds like a very similar arrangement.
I did have a look at all the fuses in a box in the engine compartment,
several of which seemed to be related to the fans. None of them "appeared"
to be blown, but I must admit, I did not pull and electrically test them
individually. I will do that!
Just out of interest, do you recall if (with your problem) your fans ran on
"slow" if the air con was turned on ?
Thanks again for the info,

- Steve

 

Yes when I had problems with my Xsara, the fans also ran on a
slow speed (both fans) when the air con was turned on.
After replacing the fuse and running the engine stationary to get
it warm, so the fans would start rotating, It saw that only one fan
was rotating and not both fans. I returned to the dealer and
told him the whole story, he replaced a hose (??) of the air con
and the problem was solved.

Is it a original PSA Air con build in from the factory or a non PSA
air con build in later, like I had in my Xsara. In that case, look for
a cap you can remove, by pulling it up, there is another fuse for
the air con. Also check, if the air con is really cooling? If not? than
it must be a fuse.

You are lucky to have a 306, I had to turn-in my 306 break XTd,
since the lease contract for this company car was over. I had a
Opel Astra (Vauxhall? in GB) till sunday, but made a accident with it.
Now I have a Nissan Almera Tino, also a shit car like the Opel.
Tommorow I will receive a Opel Astra Diesel for some 3 months
until my new 406 Break 110 bhp HDI is arrived.

 

Thanks, VTR, that's helpful.
Yes, my Air Con is an original factory fit.
I'm going to double-check all the fuses (etc) this weekend, but at the
moment what would really help to know is where the damn fan control box for
my 306 lives! Somebody must know... Paging Mindwipe.. paging Mindwipe...

- Cheers
- Steve

 

It is a pity I can't help you, I had to give my 306 back to the
leasing company. For an original factory fit aircon, there is a
main fuse under the bonnet, I think it is fuse nr1, that is for
the fan or Aircon. Is your 306 a 1.9D Diesel??

I have a (Dutch) technical manual of the Xsara 1.9D, I can try to
look up for the controlbox tomorrow, If can find the damm manual.
For now it is too late, I have to drive tomorrow to that stupid
stinking city called Amsterdam for my work.

Cheers,

Sohail (Rotterdam, the Netherlands)

 

It's under the N/S wing behind the plastic protector, just above the
horn(s). Black (I think) unit with a multi way connector to it. You
pull the red slide along while pulling the connector off.

 

Nigel,

Thanks so much for replying to my post. I just found some info on an aussie
group that suggested the control box was
in the place you suggested, too.
BUT - guess what - I've just this moment taken off the cover, and had a
really good look in that area - can't find anything !
All I can see is the horn, and wiring to the fog lamp. I even had a feel
around above the horn. I'm sure that I would have seen it.
I wonder what model of 306 your experience is based on? Do you think there a
possiblity that the fan control is done by the main ECU on my car? (I hope
not)
On the other hand, there IS an interesting little box mounted behind my main
ECU. I'm wondering if that could be it ?
It's about the size of a packet of cigarettes, brown, with a multi-way
connector plugged in the bottom. On the top there are some schematic symbols
moulded into the plastic, but I can't read them at the moment. It's fixed on
with one bolt at the top.

Thanks again though - Any further ideas most greatly welcomed ! I'm really
keen to try and solve this problem now I've got my teeth into it....

- Steve

 

I'll try to find out for you tomorrow. You say it's a late model but
what reg is it? Is it petrol or diesel? HDI?

 

Sorry, Nigel.
It's a 2000 model 306 "Meridian" 1.6 Petrol
Not long out of warranty.. typical !
Many thanks for your efforts ;-)

- Steve

 

OK, I've found out a few things. The fans are controlled on late model
cars by the injection ECU.
First thing to check is the three relays (2 green and one purple),
possibly by substitution. Then check the resistance of the fan
motors--should be no more than 1 to 1.5 ohms. Another problem area is
the round connector to the nearside of the radiator toward the bottom.
Unscrew it and make sure there is no water or corrosion on the pins.
also check the loom as it can chafe on the plastic mounting for the
fans, We have had two cases of chaffing through the wires.
There may be on the thermostat housing somewhere, three connectors--a
blue one, a green one and a brown one. I think they're all two pin
types. With the engine running, and the air con switched off
disconnect the brown one, and the fans should run at full speed.
If there is still no joy then it may be down to a broken wire
somewhere, which will be a nightmare to find and fix.
It could be the ECU itself, although we have had no cases of this. The
usual cause is the relays or the feeds and earths to and from them.
Good luck.

 

cars by the injection ECU.
<snip>

Nigel, thanks, that really is incredibly helpful.
I was indeed starting to suspect that the fans were controlled by the main
ECU (possibly Motronic 5.2?)
The box I suspected might be the fan controller was indeed marked "Bitron"
but turned out to be a twin relay so that was a red herring. I even
double-checked the recess where people told me to look for a controller, but
there was definitely none there.

A couple of points I'd like your opinion on, if you'd bear with me: (tell
me if you disagree)

* The fans themselves must be OK because they do run slow with the air con
on.
* I've found and fully electrically tested the three relays you mentioned so
they must be OK too.
* I have also confirmed that 12V power is getting to the left-hand and
right-hand fan relay sockets.
* I have tested all fuses in the passenger and engine compartments.

Concerning the sensors, I can only find two that look as if they might be
applicable, both near the thermostat housing.
I imagine that one of them might be the dashboard gauge sender and may only
affect the indication (which works OK)
I've put 4 pics up on http://www.backstreet.demon.co.uk/carpics.htm to avoid
posting here.
In particular, look at the 4th (last) picture if you can.
I think that the thermostat fits in the bottom of the picture.
There is one vertically mounted sensor with a blue connector and 3 wires. Is
this relevant? With 3 wires, I wondered if it could be a combination of more
than one sensor.
The blue connector with 4 wires appears unrelated (parts of oxygen or lambda
sensor wiring I think?)
Notice the little blue "blob" I have arrowed in red - This is part of
another sensor with 2 wires tightly tucked in behind the thermostat area.
Perhaps this is relevant too?
But, alas, so green or brown ?
As you say, I can try disconnecting them - But I'd value your opinion before
I try!
I really do hope that it is wiring or a sensor - A new ECU sounds a horrific
prospect.

- Steve

 

So you have a TU5 engine? Ahhh, right. You may have to forget what I
said about disconnecting the brown plug! I think I will have to
consult the workshop manuals tomorrow. Could you today send me your
VIN number and your build code (which is on a sticker either on the A
post adjacent to the door hinges or on the edge of the door below the
lock. There is a chance it is behind the N/S strut turret in the
engine compartment, behind the bulkhead, where the air inlet to the
heater is. I just need the first four digits, disregarding the first
digit if it is a zero.
I agree with your four points. But maybe check for any earths on the
relays.
If it gets to the point where the ECU is suspected, then I suggest you
take it to a Peugeot dealer (if you have one where you live that you
trust!!) where they can interface in to the ECU with their BIP and
properly test the circuit out. This may be a bit expensive but not as
much as a new ECU when it wasn't the problem!!
Of the two blue sensors in your last photo, I think one does the gauge
and the other is for the ECU, but I shall have to check in the manuals
tomorrow which is which.
Just for the sake of it have you disconnected the plug in your first
photo by the side of the radiator and checked for corrosion etc?

 

Just another thought. How hot have you let the engine get? Is it only
the slow speed that doesn't work? Have you let it get hot enough to
try the fast speed (with the aircon off of course!)? This will be
pretty close to the red on the gauge, so be careful.

 

<snip>
Nigel,
Great - sounds like we (ok, you!) are getting somewhere.
The sticker on the door pillar carries the following numbers in 4 lines:

0874 981
20186
EGED**
3316XXXX

Note: let me know if you need numbers XXXX above.

I've not checked the earths for the relays yet. Will do that soon.
I did disconnect the 3-wire sensor (with ignition off) and tested it. It
read around 10Kohms between two of the pins at 12C. Then I warmed the engine
up a little, and it decreased to around 300 ohms. The 10K ohms seemed a
little high for a typical sensor at ambient, but I guess it might be OK. The
third wire seemed to remain low-resistance to earth.
I tried disconnecting the electrical plug to the radiator. All the pins
looked bright and shiny, but I gave it a dose of switch cleaner anyway
before reconecting!
I'll be away from the computer until late Tuesday - Good luck!
-Steve

 

Good question. The only times it has got really hot is when I have been in
busy traffic, and the STOP light came on.
I can't remember the exact indicated temperature - well over 100 I think - I
was rather busy trying to find a place to actually STOP...
I pulled over, gnashed teeth a bit, noticed that the fan's weren't running,
and switched off.
So far, in testing, I haven't let it get above 100. I'm sure that the fans
should be running slow before that.

- Steve

 

Well, in the faint hope you're still there, I need your VIN number,
the chassis number, beginning VF3 and having 17 digits. I'll try with
just the build code.

 

Oops, sorry - I saw the label contained similar information, so I didnt
bother with the full code:
VF37ANFTF33164219
Cheers!
-Steve

 

The fan control is the ECU. It takes its information from the water
temperature sensor. You have two, according to your photo. The one
that sends to the ECU is the three wire one on top. The other one you
can just about see is for the gauge. I suggest you try a new one of
these (part number 1338A6).
I also found out that the fans should come on slow when the aircon is
switched on, but when the aircon is going flat out, then they should
run on fast. (By the way, it was unclear on the parts page for your
chassis number , how many fans you should have!! I think you said at
the start of this you had two, yes?)
You might want to check the earth point, which is just in front of the
battery carries, on the chassis. Take the bolt out and clean
everything. Make sure the bolt is tight afterwards.
If all this doesn't work, then you will have to bite the bullet and
get your dealer to put it on the Diag, to find out whether the ECU is
receiving the information from the sensor, and if it is also earthing
the relays to get the fans going.
Good luck.

 

<snip>

Nigel,
Thanks, that is really invaluable information.
I have access to an almost identical (but less faulty!) car tomorrow, so I'm
going to try to persaude the owner to let me measure the sensor resistances
on his! That should help. I'll let you know....
Cheers -

- Steve