HDI radiator fans constantly on.

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charentejohn
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HDI radiator fans constantly on.

Post by charentejohn »

I am answering my own question really as I found the answer here http://community.preloved.co.uk/forums/discussion/80839" onclick="window.open(this.href);return false;
I searched this forum but no results for this so thought it worth posting a link.

I tried what they said which is to take the heater controls off screen demist.
I noticed the fans were always on and couldn't figure out why, seems demist is, or thinks it is, using the air con so turns the fans on. Moved the control to another setting and they stopped.

I was worried as the car ran really cold but it had the thermostat removed (just fitted a new one). Between that and the fans always on it is amazing it didn't ice up.....
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Re: HDI radiator fans constantly on.

Post by CitroJim »

No wonder it ran cold John :lol: It would certainly not have been helped running with the A/C on all the time but at least it cuts itself off if evaporator temperature drops below 5 degrees.

The relationship between demist and aircon is know about... In fact there was a few posts on here quite recently discussing which Xantias did and did not have the feature. I don't think that one's still fully resolved now :roll: The thread in question will be hard to find as it's likely it's buried deep in some other thread as an 'off-topic' - something this forum is a bit well-known for. It makes for an interesting forum but makes searching for a particular topic a bit of an art... :twisted:

Just a note on thermostats. The HDi, in common with may other PSA engines, uses a 'Top Hat' thermostat which has a separate disc to close off a water bypass channel when the main part of the thermostat opens. This is all done to increase the speed of warm-up, especially to the heater matrix.

Running without a 'stat means this bypass channel does not close when the coolant is up to temperature and effectively creates a water 'short-circuit' around the engine that diverts most hot water away from the radiator. Not a problem perhaps on a lightly driven HDi in the winter but in the summer it could cause serious and dangerous overheating.
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Re: HDI radiator fans constantly on.

Post by citroenxm »

Well I would have responded with a guess as you do not say, that your Xantia is a W, X or a Y reg model, as you have guessed it... the Air Con switchs on when "Windscreen Demist" is selected to help increase window demist time..

I keep saying, Air Con is NOT just a Cold out put device, its also an Air De-Hymidifier... In that it dries incommind Air. You can still have the Heat slider on Hot with the air con on.. With this you should find ALL windows, not just the windscreen will demist very rapidly.. This is of course assuming the Air Con system is in full working order. Even though the fans come on, is the Air Con compressor kicking in too??

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Re: HDI radiator fans constantly on.

Post by addo »

CitroJim wrote:...The HDi, in common with may other PSA engines, uses a 'Top Hat' thermostat which has a separate disc to close off a water bypass channel when the main part of the thermostat opens... Running without a 'stat means this bypass channel does not close when the coolant is up to temperature and effectively creates a water 'short-circuit' around the engine that diverts most hot water away from the radiator...in the summer it could cause serious and dangerous overheating.
Yes; some todgers took the thermostat out my PRV-powered 605. Effing stupid.
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Re: HDI radiator fans constantly on.

Post by charentejohn »

Sounds like taking the thermostat out would not really stop overheating ?
A dumb thing to do anyway but this car was used in Portugal (and so Spain) for some journeys, so heat would be a problem.
Seems removing the thermostat to stop overheating would not necessarily work. I don't think the head gasket has been damaged replaced, running ok and doesn't feel like there was a problem, if you know what I mean.

Car is a 2001 HDI 90 SX

I still have to understand the heat/cold system, and the guy I bought it off said the heater blower had been replaced. Humidiy/temp sensor and fan which controlled humidity, very hazy as to what this does as such, my manual is in french.

Can anyone explain what happens when the screen demist is selected. From what Ciroenxm is saying is that in this case the air con is on but not blowing cold air, just the dehumidifying aspect being used.
Damn clever if this is the case, so....
With Air con off, all settings apart from screen demist will just blow hot air depending on temp setting.
But... if screen demist is selected the air con system will kick in demists all windows while dehumidifying the air in the process. Good to know if the car is misted up that the heater is not just blowing air but removing moisture as well.

I did notice that, with demist selected, the car did not mist up despite being really drizzly and damp at the moment. I assumed it was just lucky, but seems it may be deliberate design.
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Re: HDI radiator fans constantly on.

Post by citroenxm »

As long as the air con system has the air con system fully gassed up with r134a gas then the air con will work correctly... You will know as you will hear a prominent "click" from the compressor... The air con rad in the car and the heater rad are two seperate things... So the incomming air passes through the air con rad which cools and dries it out then if the heater slider is on hot is then directed through the heate matrix... Of coure if the heater temp is set to cold you get your airconditiond air then.. But its still dried air.

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Re: HDI radiator fans constantly on.

Post by Dommo »

I know both my Activa (T reg '99) and my 2.1TD SX (1997 s2 R reg) turned the AC on with the windscreen demist setting, but my '97 s1 VSX r reg doesn't. Despite being r reg I think it's actually a '95 car
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Re: HDI radiator fans constantly on.

Post by citroenxm »

S1 cars dont do it.. S1 cars did go up to 1997 thats the model change in 1997 and is a s2 revision... I just cant understand how all you fourm members cars do it but ALL my s2 models ive had prior to Late W reg to x reg models have not done it.. And ive had and been involved with a fair few... My V reg exclusive does not do it... My mates T reg exclusivee does not do it.. Nor did his T reg sx do it either.. My first T reg Sx did not do it.. My customers early W reg sx does not do it but a later W reg lx i had in did do it.. So does a customers X reg sx also does it.. As have both my mums x reg lx and her y reg lx both do it.. Ive another customer with an r reg s2 lx doesnt do it also another T reg lx doesnt... So as far as im concerned from what ive whitnessed here its only late W reg cars onwards....

Ive got a V reg hdi 90 in.. Ive not tested that one yet....

This is all very strange surely all the ones ive come across have not been faulty! By the way I do also mean air con on WITHOUT the dash button press ON....

Paul
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Re: HDI radiator fans constantly on.

Post by CitroJim »

Don't worry Paul, all those you've tested so far have been special Welsh Market ones. It's only those for the English, Irish and Scottish markets that do it... :wink:

The V reg 90 HDi is an ideal candidate to donate me a flap gearbox.... :lol:
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Re: HDI radiator fans constantly on.

Post by citroenxm »

:shock: :o ... Cant do that jim.. Its too complete and doesnt need a matrix just yet.. :P

the cars i have above were some were english... My first t reg sx hdi was from essex

paul
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Re: HDI radiator fans constantly on.

Post by charentejohn »

My car is a French one (so no doubt made in Spain :-D ) and, just to clarify things, the fans come on when set on demist with the aircon dash button set to off.
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2008 Peugeot 207 Sw 1.6 16v hdi. 217k and rising
2010 Peugeot 207 SW 1.6 8v HDi 161k and rising
x 70

Re: HDI radiator fans constantly on.

Post by citroenxm »

I think citroen only made the xantia in france... Id expect yur car to do it being a 2001.. Last of line..

Nice

paul
Sharing a pug 207 1.6 hdi Sw 16v.
M reg Xm 2.1 td auto exclusive S2 269k and rising
L reg XM V6 12v SEi auto .. Light project

A very sad...
1994 XM 2.1 d auto
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