Xantia A/C

Post your Cit/Peu/Ren air conditioning queries or advice.

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Rhothgar
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Re: Xantia A/C

Post by Rhothgar »

The fan motors will consist of a commutator ring and carbon brushes just like an alternator.

The carbon brushes are held onto the commutator ring by spring pressure.

Carbon brushes can and do wear out.

The problem there would be trying to source suitable replacement parts.

A friend of mine recently refurbished the alternator on his 1983 VW Golf. I therefore have an account with HC Cargo who supply such parts. Identifying it would be the problem.

I’ve got to say I’m not averse to having a fo at stripping a fan motor down and investigating but whilst I think the modified socket is a genius idea I still see that there is a potential for skinned fingers if the spanner runs so close to the intercooler rad.

I think when I do mine I’ll be taking the bumper off...

Have you checked the integrity of the wiring, Colin?

To do this safely so you do not blow your ECU up, you MUST disconnect ECU connector and I would remove all relays too then you can cannot a load such as a bulb to each wire on each relay in turn to see if there is high resistance in any wire.

So, for instance, connect one end to battery +ve and the other end to say Pin 5 of relay 1503.

If you look at Fan 1511 on the wiring diagram, you will see Pin 2 of the fan is connected to earth so in order to test the wiring and the fan, you would apply 12V to Pin 1 but as you probably cannot access Pin 1, by working back you can see that you could apply the battery +ve to Pin 5 of relay 1503.

You could also apply power to Pin 4 of relay 1504.

If Pin 5 of 1503 spin the fan but Pin 4 of relay 1504 did not, it would suggest high resistance in the wiring between Pin 4 and splice E096 (which is the little ⚫️ just above Pin 4 in the diagram.

By methodically working through each wire connected to the fans, you can build a picture of the wiring integrity.

This is what I hope to do when I get sufficient time.

If you could apply 12V directly at Pin 1 of fan 1511 and a separate earth to Pin 2 of 1511 then this would test the fan in isolation. If it spun up in that case, you know the fan is good.

If you applied 12V directly to Pin 1 of 1511 and relied on the connected earth from Pin 2 of 1511 and it didn’t spin up then you would know the earth wire between Pin 2 and M4B earthing point was high resistance.

Similarly with fan 1512, although it is slightly more complicated here. You could earth Pin 5 of the connector at relay 1504 and apply power to Pin 3 of same connector. This should spin the fan but it doesn’t tell you what condition the wiring is in.

Chris speaks of resistances at some point in this topic and specifically that there may be enough power for one fan but not the other.

By systematically working through isolating each component and the wire between it and each and every connection point you can build a picture of the state of the wiring.

I guess a proper auto electrician would do initial checks like fuses and then look at the component and probably the wiring last of all. One thing is for sure they are VERY clever people when they can turn up and work through a system without a wiring diagram!!!

I hope I’m not teaching you to suck eggs here.

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

You could conceivably make new brushes from ones that are a close match by filing them to size... I've done it in the past ;)

Thing is, the motors are not intended to be disassembled... Practice on a scrap one first and see how you get on... You may have more success than I did... Taking them apart is a messy job too... They will be found full of carbon dust from the worn brushes...

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myglaren
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Re: Xantia A/C

Post by myglaren »

I used to buy FIAT alternator brushes and cut them down to replace the ones in our washing machine.

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

myglaren wrote:
12 Apr 2021, 10:18
I used to buy FIAT alternator brushes and cut them down to replace the ones in our washing machine.
And the downside of using Fiat bits was the washing machine rusted away after completing the next wash cycle :lol:

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white exec
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Re: Xantia A/C

Post by white exec »

You absolutely MUST check that each of the two fans is working properly, by connecting them directly to a 12v supply.
Expect each to pull about 16-20A, and maybe twice that on starting, so fuse at 30-40A for doing tests.

Alternators and fans both have carbon brushes, yes, but the copper surfaces they operate with are different. An alternator is an a.c. generating device, and has continuous, smooth "slip rings", and the brushes and slip rings actually handle quite a modest control current - just enough for the rotating wound armature. The hefty output current (could be anything up to 150-200A these days) is pulled off the non-moving "stator" windings, surrounding the rotating armature, and then rectified to d.c. by a small bunch of heavy-duty diodes.

Fan (and blower, and electric drill) d.c. motors have brushes, too, but the copper surface they run on is "segmented" - so the running current is fed to parts of the rotating armature in sequence, to make the magnetic fields operate correctly. Importantly, the FULL MOTOR CURRENT goes through these brushes and segmented commutator, which is why they eventually suffer wear and arcing, and give up.

Please, test the fan motors FIRST.
Then the Relays and their connectors.
Then, maybe, the wiring itself.

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

white exec wrote:
12 Apr 2021, 12:25
Please, test the fan motors FIRST.
Then the Relays and their connectors.
Then, maybe, the wiring itself.
Excellent advice Chris ;) :)

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Re: Xantia A/C

Post by admiral51 »

Chris i totally understand what you are saying with testing the motors with a direct feed as a first point of call, now if you could wave the magic wand and get the fixings the other way round so they are easy to remove ....... :)
Actually Jim if you pop into this thread can you confirm if it is possible once the motors have been removed to swap the bolts/nuts so the nuts are in the front not the back, old grey matter again seems to recall.........
I guess this it turning more into a mini blog rather than a specific diagnostic thread with my idle thoughts and ramblings but if i keep a record of what i have done then i can recap and go back to see what i have missed out on doing, the first being remove the fans and putting a direct feed to them :(
But as promised i did have the fans running over the last few days as they should with the odd small flick on the L/H fan and i said i would try them on a long run to work 35 miles ish.
So this morning it was -2 here at 4am started her up ,A/C button pressed and blower on and set to demist and not a peep from the fans, gave them both a few severe flicks with the screwdriver and nothing, bugger it was cold so sod it back into the car and let the heater clear the screen.
Left setting as it was when i started her up and when i got to work still no fans working.
So 14 hrs later when i started her up to go home with nothing changed settings wise just out of curiosity i popped the bonnet, both fans spinning at slow speed. Now i know my temp gauge and on the trip home it was sat at around 75 ish, below the 80 ish it normally sits at. Got home, popped bonnet and both fans were still spinning quite happily.

Not sure what else to post until i can remove the fans and test the motors directly with 12v and i really appreciate every ones input but i have found that both fans work in situ as they should, albeit not all the time.
So in my head i think i need to just keep trying to get them running by having the A/C button in and or set to demist until i can remove the fans themselves.
Going to go and sit in the naughty corner and have a good chat with myself :)

Colin

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

admiral51 wrote:
12 Apr 2021, 22:58
Actually Jim if you pop into this thread can you confirm if it is possible once the motors have been removed to swap the bolts/nuts so the nuts are in the front not the back, old grey matter again seems to recall.........
Ni sadly not Colin :( If only... It would make it so much easier...

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Re: Xantia A/C

Post by admiral51 »

Oh well never mind Jim i think they will be staying put for a while. :(
I think i am going to have to wait for warmer weather in the morning to test my latest in a long line of random theories about this issue to destruction.

I am working along the lines that the A/C will work without the fans actually running and also that it is not just the A/C ECU and temp sensor that control the fans but also the engine ECU plays a part.
So as with yesterday morning the temp this morning was -2 and never rose above zero on my way to work and with settings the same as yesterday no fans were working.
However, same as yesterday when i left work today the temp was 11 degrees and as soon as i started the car up with the same settings both fans were working and they continued to work for the entire journey.
My thinking if you can call it that, is that if the air intake temp is zero( ish ) or below there is no need for the fans to be running to aid cooling particularly with a cold engine and so if we accept that the A/C will work without the fans running ( still need to get mine gassed and tested ) then could the engine ECU actually be able to over ride the power control to the fans and keep it switched off until other parameters are met.
Everything else seems to work as it should. Unplug stat plug both full speed, set to demist they both run at slow, same as when A/C button is pressed with blower on but previously tested with outside temp well above 14 degrees.
So why when it is zero or below do they not work, the car has been left for well over 11 hours each time the last 2 days and with 11 degrees of temp they work :?

Promise last update for a few days unless anyone chips in with an address and number for the men in white coats to take me away :oops:

Edit I guess the only other way to test the fans working in situ and not disturbing them in sub zero temps is to unplug the stat plug to create an over heat situation for the various related ECU's. I will try that but would prefer to do it at around 6-7 am not 3:30 tomorrow when i need to leave for work :)

Colin

Rhothgar
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Re: Xantia A/C

Post by Rhothgar »

No need to do that Colin.

To test fans independently, unplug both top relays and apply 12V only direct from battery with IGN ON, to Pin 5 which should be the bottom pin in both cases and you will get slow speed on one pin to both fans and high speed to right hand fan when viewed from front in the other relay pin 5.

I’ve got my slow speed working with the ‘Colin Approved Hammer Method’. I simply tapped it and a little dust came out so I powered it and kept whacking it until no more dust was ejected. 👍

I’ll upload a video to my OneDrive and post a link here as there is a question for Chris in there.

It seems the relay position shown in the factory manual are actually incorrect from what I can make out.

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

Here's my special tool for getting at the 10mm fan motor fixing nuts without needing to remove the rads and A/C condenser...
xantfantool.jpg
Having a 13mm hex on the end means a ratchet spanner can be used and that makes the job even easier...

Colin, it'll soon be on its way to you ;)

Once you have used it I expect Roger will then need it!

admiral51
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Re: Xantia A/C

Post by admiral51 »

As always Jim you are an absolute star =D> =D> =D> :-D

admiral51
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Re: Xantia A/C

Post by admiral51 »

Jim it arrived today and i also have return address =D> =D> =D>
May need to wait till the weekend before i get to use it in action.

Thanks again, a star as always.

Colin

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CitroJim
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Re: Xantia A/C

Post by CitroJim »

admiral51 wrote:
19 Apr 2021, 18:29
Jim it arrived today and i also have return address =D> =D> =D>
May need to wait till the weekend before i get to use it in action.

Thanks again, a star as always.

Colin
Great to hear the Post Office did a good job Colin :)

No rush for its return, I'll not be needing it any time soon!

admiral51
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Re: Xantia A/C

Post by admiral51 »

Well been a while but finally i have 2 working fans.

Thanks to Sir Jim and his special tool and the fans he sent.

However it was not as straight forward as i had hoped. Had a minor problem with one of the bolts which had managed to turn in the mounting as i was undoing the nut. Surprising as the amount of rust around the mounting was the only thing holding it together :(
Managed to undo the other 2 nuts and worked the motor out leaving the bolt and nut plus a little bit of rusted metal attached and with a piece of wood carefully placed i removed the offending nut and bolt. No such trouble with the other motor.
So a bit of contact cleaner and thread lubricant the 2 new motors were back in place and as they were sold as tested and working from Sir Jim i knew they would work so imagine my shock when they didn't, not even a hint of movement. :? :cry:
Then the penny dropped, they were not the ones Sir Jim sent me, similar box but from my stash of spares purchased in a job lot. #-o #-o
So removed them again and fitted the correctly supplied ones and bingo everything working as it should. :rofl2: :-D
So yes you were all correct it was the fans at fault all along =D> :oops:

Colin