Cooling Fans

[mattgreene]

Im guessing this has been spoke about before so feel free to move it lol!
Right, my 306 hdi, tested the air con and it didnt leak!! So ive gassed it up and it works ok the issue is the compressor clutch cycles quickly, and the fan doesnt come on when ac button pressed, basically i've checked all the fuses and tested the relays under the grille, checked the multiplugs too, so im stumped where to look next, ideas please

Matt

[Niall]

Almost guarantee it will be the controller unit which is behind the passenger front bumper under the headlight. Normally referred to as the Bitron unit.

[mattgreene]

Ah rite ok then, any easy way of testing??

[Niall]

Yeah when the engine is running, unplug the brown plug on the thermostat housing and leave it a few seconds. The fans should both kick in full speed. If not, replace that unit.

[mattgreene]

ok then if that works ok what would be the next step

[cully]

hdi fans are controlled by the ecu there is no fan controller bitron unit like petrol and earlyer cars,
i sespect you have fan issues due to the fans themself not working or the relays or the temp sensor on the block or as nial says the multiplug on the fan assembly

turning on a working Ac system brings the fan on in slow speed both fans are connected in sieres if one is broken both wont work!
when the car gets to temp the fans run at high speed both are in parrellel if one is broke only one will run

[mattgreene]

ah right that makes sense, ill test the fans by removing the blue/brown plug from the stat housing and see if they come on then, i gassed up the air con about a hour and a half a go with no leaks!!
does the climate control have a ecu separately? due to when i turn on the a/c it clutch clicks in but the engines revs don't pick up, maybe they don't on these but other cars do.

[cully]

yes it picks up a little not much

if you can deffo hear the clutch clicking you have gas
as there is a pressure switch which stops the clutch engaging with no gas

[mattgreene]

yeh deffo gas in it, clutch clicks every time, does the pressure switch control the fans too? have read somewhere about controlling the fans with the ac switch

---

just read somewhere the fans do not some on below 5*c outside temp, safety feature built in ecu to stop gas freezing in the condenser.............apparently!!

[cully]

if you unplug the pressure switch
then bridge pins 1-3 the fans will run at full speed when you push the AC button in the car

[mattgreene]

ah ok, another test does 'fans do not some on below 5*c outside temp, safety feature built in ecu to stop gas freezing in the condenser' sound right to you?

[cully]

your reading this from the 6 forum arnt you

[mattgreene]

yeh probably!! my bad lol

[mattgreene]

tested the fans today, only the one on the right from drivers seat works, so im guessing i need to replace the left one?? am i right?

[cully]

yup replace the one that dont work and your system may work ok if there are no other faults

i had the same problem with mine i never saw the fans running so tested the fans and found the O/Side fan not working
i replaced the fan motor and it all worked fine

there are different types of motor so make sure you get the right one
the fan blades on mine are held on with a screw in the centre of the blades it is a left hand thread (clockwise to undo)

[mattgreene]

cool thanks for that cully