Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

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white exec
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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by white exec »

Your 'warp drive' is just fan at max (High) speed - quite normal, and shows the ECU is working ok, as are the fan and the fast speed relay (#1509). More progress!

Replace the temp sensor next - they are a variable resistance that can go 'out of range', and a fault with them is not unknown. Replace with the correct type and part number, preferably from Citroen.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by admiral51 »

I never have been known to phrase a question the correct way, apart from when SWMBO said yes, from memory the only time she said that, think i say yes now more than i used to #-o #-o
Its all progress you are getting there, a car with a fresh 12 month ticket, and a fully paid up member of the Citroen " WTF" wiring community :rofl2: :rofl2: :-D

wheeler
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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by wheeler »

Lets go back a step here, why are you going to replace the sensor?
What happened when you disconnected it is totally normal, doesent sound like there is anything wrong with the sensor to me.
Yes its certainly not unknown for PSA coolant temp sensors to fail, I've replaced more than I can count over the years but when these NTC sensors go faulty the almost always cause the cooling fan to come on full speed, tell you the engine is overheating when its not & very difficult starting when cold. The system is designed to fail safe if the sensor goes faulty.
Do you have access to live data on a diagnostic reader? that's the easiest wat to see what the sensor is doing. If not you can use the table below to check the resistance at a given temperature.
Attachments
NTC_CTS.jpg

Fartblast
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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by Fartblast »

That looks interesting, I'll check it with my multitester and let you know. Thank you again!

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by admiral51 »

Thinking logically about the car, no idea of the reg or any advisories, but it passed the emissions test, so a healthy engine, you dont mention any issue with it apart from the fan issue, A/C is working, may or may not be getting as cold as it should, maybe a regass check later will help.
You say its worth £500 maybe, no idea what you paid for it but £43 on parts + test is around £600 all in if you paid £500 for it.
Forget fuel/tax/insurance for a minute and with a little more expense circa £50 thats a cheap car over a year, works out really cheap when you work it out per day :)

admiral51
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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by admiral51 »

If the sensor was to fail totally then it should put the fan on high speed all the time ?
When unplugged it gets no signal so therefore no signal to the ECU so fan on full speed after a given time frame within the ECU?
Should it not put the fan on slow to start with and then full speed as the relays need to be instructed to do their stuff ?
If the sensor is giving an incorrect reading but within parameters until the temp gets to a point that the various ECU cannot work out what info is correct they go to default settings?
Just asking as i have limited understanding of how these systems work just thinking aloud :)

Way too much time in lockdown lol

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by myglaren »

I had one fail on my C5 - the green one.
When the car was started after being stood overnight it would flag up a warning and the temperature gauge would show max, right up in the red.
New sensor soon fixed that one.

Couldn't say about the fan though, I have never heard mine running since I bought the first C5 16/03 2007.
Have installed a new fan in the current one a couple of years back as I discovered while idly poking at it that it was seized. No idea if the new one works or not. Aircon is buggered.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by Fartblast »

admiral51 wrote:
03 Apr 2020, 19:00
Thinking logically about the car, no idea of the reg or any advisories, but it passed the emissions test, so a healthy engine, you dont mention any issue with it apart from the fan issue, A/C is working, may or may not be getting as cold as it should, maybe a regass check later will help.
You say its worth £500 maybe, no idea what you paid for it but £43 on parts + test is around £600 all in if you paid £500 for it.
Forget fuel/tax/insurance for a minute and with a little more expense circa £50 thats a cheap car over a year, works out really cheap when you work it out per day :)


I have three relays that came with the fan assembly from the breakers yard, I'll fit them and see if they make any difference.
I bought the car brand new back in March 2003 and have not spent a lot on it, things like tyres, tracking, broken spring, 2.5 exhausts, 2x coil packs, brake discs and pads, battery, and a few other bits. Its only done 52200 miles and spent most of its life parked on the drive. Ive being running it for years without a working fan so another year wont make that much difference.

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white exec
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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by white exec »

These sensors are temperature dependent resistors, and should change pretty much linearly across a range. They can fail by going open circuit - akin to disconnecting - which the ECU interprets as a very high resistance (= very high temp) and so puts the fan on max blast.

They can also fail 'short circuit', which seems to be unusual, and I'm not sure how the ECU interprets that. Could be by assuming very low temp, so fan just stays off.

They can also fail by going inaccurate, in which case expected fan (and gauge, and maybe injection) operation - Off, Slow, Fast - can go into unexpected territory.

As reported, they can and do fail.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by xantia_v6 »

It is not clear to me that the vehicle currently has any fault. You can spend a lot of time and money fixing a non-existent fault.

I would suggest that you actually measure the temperature of the coolant, via diagbox or an accurate thermometer before proceeding.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by Fartblast »

Overheating was the reason the original MOT was aborted and today the MOT tester turned up the cabin heater and fan to help cool the engine, as the radiator cooling fan did not work.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by xantia_v6 »

Fartblast wrote:
01 Apr 2020, 18:01
UPDATE:
Fitted the new (breakers yard) fan off a 2003 Picasso and although the housing was dirty and had obviously covered allot more miles than my car, the fan motor seems to be working fine,
You have not really provided any evidence that there is still a problem after that.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by wheeler »

xantia_v6 wrote:
03 Apr 2020, 22:34
It is not clear to me that the vehicle currently has any fault. You can spend a lot of time and money fixing a non-existent fault.

I would suggest that you actually measure the temperature of the coolant, via diagbox or an accurate thermometer before proceeding.
Aggred 👆🏻

Was the car about to overheat again during the re test or was the tester just putting the interior fan on as a precautionary measure?
Putting the interior fan on would probably stop it getting hot enough to need the cooling fan.
Yes It’s certainly possible that the sensor may be reading slightly incorrectly but im basing my advice on my actual findings over the years, like i say ive changed more of these than i could count but never for the symptoms described above. If the CTS was faulty i would also have expected to see other symptoms like false overheating warnings when the engine is cold & staring issues especially when cold.
If you dont have diagbox/Lexia even the under £10 on ebay ELM readers will read live data of the CTS.

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Re: Radiator Fan NOT Working Xsara Picasso 1.8sx 2003

Post by white exec »

An accurate coolant temp check is the way to go.
Check it at the thermostat/temp sensor/water outlet housing, with a fully warmed-up engine.

Normal running temp will be around 90C, with the fans operating only when 95/98-ish is detected, and fast fan speed 105-ish.

An infra-red contactless thermometer (best pointed at a black surface, so use a bit of tape or black marker, if needed) is cheap enough on Amazon. Removes all the guesswork.