HELP!! Xantia Cooling Fans Driving me nuts!!

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Zelandeth
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Zelandeth »

Think we really need to get the car on a Lexia and see what it's reporting for temps. The key here I think is that you're reporting that the fans sometimes start at low speed. If it was a wiring fault downstream of the ECU I would expect them to be either on or off. If low speed is also involved my gut feeling is that the ECU is calling for cooling incorrectly.

If memory serves, the fans should not start before the engine though...pretty sure even with the Bitron disconnected on mine the cooling fans are one of the circuits that don't start until the engine is running. Odd that yours doesn't seem to behave the same.

Get it on the Lexia and see what it's doing. Worth remembering here that used (and even new!) replacement parts aren't beyond suspicion. At least once you can see what the car thinks is going on it should narrow your search down a bit.

If I was nearer I would happily lend a hand and see if we could get to the bottom of it - sadly am at the other end of the country now despite spending my first 29 years around Aberdeenshire and seven of them in Aberdeen itself.
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by xantia_v6 »

Being a 1.9 TD, there is nothing that will report engine temperature to a Lexia. There is no engine ECU for the mechanical diesel pump, and the Bitron fan controller can't talk to the Lexia.
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Zelandeth »

Oh...didn't realise that temp wasn't reported. Knew the data on a TD was limited, but thought it would still be able to see some status info on vehicle systems like the fans. Do confess to never having used or even seen a Lexia (yet).

Looks like it's back to old fashioned systematic fault finding then...

Failing that a separately powered thermostatic fan is a perfectly valid solution I think - I would feed it from the battery direct though (via a suitable fuse and relay of course). Just because you have a fault meaning they are always live now doesn't mean that will remain the case...so I wouldn't risk using that as a power source. If you're going down that route I would just eliminate the Bitron etc completely from the circuit.

Remember that you can feed power to the fans in this setup via a spade terminal inserted into the respective slots in the fan relay box - saves taking the whole nose apart to get to the fan power wires directly!

Remember when setting this up that you'll also want to have the relay(s) fed when the A/C is active. Easy enough to do though, just run a feed from the 12V supply to the compressor clutch to your fan relay coil - via a diode so you don't have issues with the circuits interacting. If this sounds a bit complicated let me know and I'll draw it all out - there's less spaghetti involved than it sounds like.

I'd always rather fix the original fault in an ideal world, but it sounds like this may actually be easier given what you've already tried...plus you know it should be reliable, important as XUDs don't like getting hot.
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by c.morewood »

I gave Alan (Ecohouse) my Lexia to play with whilst he's away on holiday..The lapto also has a screen record facility so maybe he might be able to record something whilst driving.. We had the Lexia on the car yesterday for a while .. no pertinent error messages and as Xantia_v6 says, Alans TD which is less than a year away fron my Hdi and identical in every other respect has a lot less sensors available to be read by the Lexia so I'm not sure the Lexia will help in respect of the fans.
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Stickyfinger »

well mine can read the engine ECU and thats it ....zippo all the others
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by ecohouse1 »

Thanks Chaps. I connected Chris's Lexia over the weekend and it is limited as to what it can get access to from the car. Cooling fans did not seem to be accessible.

Couple of interesting observations though.

Rev counter stopped working whist running tests - started Ok after disconnection.

Engine temp readings were all over the place. Started engine whilst slightly warm so temp started c41 degrees then slowly rose up to about 50 then all of sudden, screen is reading 13 then 22, then 18! Dash temp guage was normal. Very odd. Which sender is it getting these readings from! There were no faults recorded of any note.

Stripped off the whole front bumper and support to access fans but couldn't see how to get behind the relays. I thought the fan unit would just lift off but it seems to be attached to the air con radiator and would come off. Anyone know how to get into the wiring behind the fan relays? Do the relay mounts full out forwards? I tried this and although they rotate 10-20 degrees they do not appear to come forward?

Cheers

Alan
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Clogzz »

The relays pull out towards the front.
Rotation is free play in the sockets.

If both fans always do the same thing together, then there is no fault in the relays.
Speed control faults are caused only by the Bitron; the sensor; and the plugs, sockets and wires from the sensor to the Bitron.

Pins 7 and 14 go to the sensor.

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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by ecohouse1 »

Hi Clogzz. I did check resistance between the bitron "plug" and the sensor- but just the wires from the sensor plug and the relevant pins in the bitron plug. Though was using an old guide based on a 306 so will double check that it was pins 7 & 14. When I checked a few weeks ago, they seemed fine with little or no resistance in the wiring but I din't check the sensor resistance at the plug. Will check again this weekend. Whats interesting now is that the fans ALWAYS come on at cold start either while the glowplugs are starting up or immediately after the engine starts. Run for about 2 minutes full tilt then shut off. Annoying as hell. Rarely now run on warm starts, but do activate when the engine hits over 90 degrees as normal. Even wondering it its a voltage drop thing......

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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Clogzz »

Hi Alan,

Probably no voltage drop because there’s enough to start the engine and run the fans at high speed.

The measurement between pins 7 and 14 with cold engine is about 1900 Ohms.
When hot it’s well over 3000 Ohms.

Best wishes and keep fiddling. :)
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by ecohouse1 »

Just thinking while I was out for lunch....
You mentioned on testing the wires that the resting / cold resistance was 1900 ohms and when hot it can g up to 3000 Ohms. Pull the plug off the thermistor, obviously resistance goes infinite hence the fams both running.

"One of the wires had 0.2 Ohms and the other one 3.7 Ω."

When you tested the wires to the bitron the difference was only 3.5 Ohms, so surely if the difference between fans off and on is several 100 ohms this small difference in the wriring wouldn't switch on the fans or am I misunderstanding something?

Like I said electrics were never my strong point! :?

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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by KennyW »

Hi Alan,

I had a similar problem a few years back on my TD. It was a broken wire between the fans and the briton sensor. All I had to do was remove the front of the vehicle to trace the fault :-D

Seriously, I had to work my way back from the fans to find the broken wire which was located at a large lock connector near to the front nearside wing.

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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by Clogzz »

electrics were never my strong point!
Your point is strong enough to get this far ! :)

3.7 Ohms won’t affect the fan switching providing that it stays at 3.7 Ohms.
My multimeter always reads wires at 0.2 Ohms, irrespective of their length or thickness.
This one was the first and only one ever to measure 3.7 in a lifetime of dabbling in electricity.
That was an indication that there was something wrong with the wire.
It was intermittent, and sometimes going open to cause the fans to spin.
Like on Kenny’s car, the fault was in the large lock connector on the inner wing behind the battery.
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by ecohouse1 »

Thanks Guys - I will revisit the area round the battery and see if I Can find either a dodgy connection or broken wire/connection. Hopefully get a chance to have a good look over the weekend!
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Re: HELP!! Xantia Cooling Fans Driving me nuts!!

Post by ecohouse1 »

By way of an update on this. Short answer was that I never really found out what the issue was! The relays at the front between the fans seem to have had suspect connections as when I twisted and manipulated them, the fans would go back to normal then after a few days revert to form of running all the time. After a particularly brutal handling off said relays, the fans went back to normal operation and have stayed there ever since, until........................................
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Nov 15 Xantia TD Cooling Fans Revenge!

Post by ecohouse1 »

Wierd how cars seem to have a 6th sense!! Days after posting that the fans had "sorted themselves out" they start up again - worse than ever now. It was -2 yesterday and snowing and as soon as the car starts, on come both fans at full speed. Howling noise and I would imagine that they will A, be loading up the alternator/battery and B, potentially overcooling the engine. Tried all my usual wire wiggle points and cleaning the brown thermistor connections but no change. Became so frustrated that I pulled the relays to stop them. Will have to keep a close eye on the temp gauge but with the weather being cold and most of my journeys open road stuff the guage has so far rarely peeped above 75.

Anyways reason for my post is that before ripping off the relays, I pulled Fuse 3 in the under bonnet fuse box - guess what the fans kept going :shock: - then pulled the 5A fuse also labelled cooling fans - no change again (not sure what the 5A fuse controls?) What is going on here then? Pulling a 30A fuse makes not a jot of difference!! Could this be a clue to the fault? Sorry Electrics were never my strong point!!

Any advice greatly received. I have decided that if by the weekend there is no improvement that I will fit my secondary thermistor bypass circuit break in the fans earth return to the inner wing so at least they will only come on at 90-100 degree coolant temp.

Thanks

Alan
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