hdi - trick to make cooling fans to come in at full speed

eurotrotter · Unread post by **eurotrotter** » 20 Mar 2011, 22:15

hey gang

i was over on pug306.net and there was a thread there that said that if u d/c the air con by unplugging a white (dirty) sensor - near the oil filter, and then d/c the connector to the condenser, and then bridge terminals 1 and 3 of this brown connector, that the cooling fans come on at full speed, whenever u turn on the air con in the cabin

i tried it but it didnt work, anyone hear of this before?

ed

Unread post by **Paul-R** » 20 Mar 2011, 23:01

Does d/c mean disconnect?

eurotrotter · Unread post by **eurotrotter** » 21 Mar 2011, 14:49

Paul-R wrote:Does d/c mean disconnect?

hi pau, ,yes dc means disconnect above, sorry for not spelling it out!

Clogzz · Unread post by **Clogzz** » 21 Mar 2011, 15:26

The dirty white connector is for the compressor clutch, so disconnecting it will prevent the aircon from working.
The brown connector goes to the pressure switch and can send the fans to high speed.
I don’t know how the terminals are numbered, so don’t know where to count from terminal 1.
The map shows the pressure switch at bottom left, with terminal numberings.
You may try different combinations, there’s no risk of fireworks.

The pedestrians won’t like the sound of fast fans.

The fans won’t last long at high speed, and the battery will go flat.

spider · Unread post by **spider** » 21 Mar 2011, 17:18

Unplugging the bitron sensor (in the thermostat housing) should also bring the fans on as it will decide that's an overheat condition. Usually at low speed for a few seconds then it will ramp them up to full.

Sometimes if you have three fan relays removing the middle one will do the same. Extreme caution: fans + fingers = not good.

Unread post by **citroenxm** » 22 Mar 2011, 15:13

I was about to say, thats a bit of an arse messing around when simply unplugging the brown sensor on the thermostat house will do the same job!!

Paul

Clogzz · Unread post by **Clogzz** » 22 Mar 2011, 16:07

From previous topics, I think that he’s got a low fan speed fault and looks into switching the fans to high speed with the aircon button when needed.

Unread post by **CitroJim** » 22 Mar 2011, 16:17

citroenxm wrote:I was about to say, thats a bit of an arse messing around when simply unplugging the brown sensor on the thermostat house will do the same job!!

Paul

Paul, does the HDi have a brown Bitron sensor? I confess I've looked and never been able to find it

That's likely more a comment on my eyesight though...

I've been running around under the assumption it does not have one and fan speed is controlled by the engine ECU...

Hot having any HDi wiring diagrams does not help either...

If it does have a sensor, where is it?

Derekofpriory · Unread post by **Derekofpriory** » 22 Mar 2011, 18:58

Hi All, as Clogzz will probably say soon, the Hdi does not have a Bitron nor a brown sensor, it has an all singing and dancing blue one that has three wires, two to the ECU for engine temp and one that heads to a connector on the inner wing near the battery, this is the one that forces high speed.

Head to "French Electrickery" for my experiences!!
as to where, it is under the intercooler to turbo hose, close to the throttle actuator doochat.
Have fun, Derek B.

Unread post by **citroenxm** » 23 Mar 2011, 10:08

Agreed - Jim, no the HDi has only ONE sensor that feeds an ECU that does all...

Paul