L.H Air Con Fan Constant Battery Feed

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nicholas6885
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L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Wed Jun 05, 2013 4:01 pm

This is my first electrical/AC problem with my 1995 XJS 6.0 in 12 years.
For no apparent reason, my L.H air con fan works continuously, even when I take the ignition keys out and seems like it is in fan position 1.
Firstly, I had to disconnect the battery, but soon removed the 20A LH fuse to stop the blower.

There is a lot of info. about these fans on the BB, but not too sure if it applies to my model year. It has the 1994-on climate control system fitted??

My initial thoughts were that it might be the 'non-serviceable' Air Conditioning Control Module.
I do believe this can be scanned, although I was hoping to sort it out myself(to try and swap another unit over).
I guess it could also be a short in the actual LH A/C blower?

If any of the above? Is it a basic job to remove the A/CCM or blower motor?

Really hoping to do a DIY job on this.

Any ideas anyone, with these later models?
Cheers,
Nick

95N 6.0 Coupe
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby almcl » Thu Jun 06, 2013 7:54 am

Not familiar with the very latest variant of the Climate Control Unit, but I think the problem you describe is common to the pre-94 models as well. There's a circuit board mounted in the fan duct and this corrodes and can produce all sorts of weird issues.

Getting a fan unit out and back is a Saturday afternoon job. You need to do this to access the circuit board which is riveted to the duct. It helps if you remove the glove box interior and have a 1/4" drive socket set with extensions to get to the fan motor bracket nuts, which are quite well buried.

Getting the whole unit out is a 'dismantle-the-interior' job but shouldn't be necessary. The ECU which controls the functions is located on the rhs of the unit and should be accessible if the cheek panel is removed.
Al McL
'93 XJS 4.0 - '05 X type Est 2.0D - '13 XF 2.2D Sportbrake

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dhdove
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Re: L.H Air Con Fan Constant Battery Feed

Postby dhdove » Thu Jun 06, 2013 5:19 pm

Nicholas

Suggest you search this section of the BB which contains some useful info.
Continuous running of a fan IS a known fault as Al suggests and is related to failure of the circuit board rivetted with two pop rivets inside the fan box which from memory is called a Darlington Resistor (apologies if its some other northern town..... :roll: )
Failure often results from water ingress from the heater plenum from air-con condensate collecting there (in considerable amounts- cupfuls!) caused by blocked drains- have you heard a sloshing sound when you go round corners :?: :!:
Removal and replacement of the fan box is a do-able DIY job, tho some electrical knowledge will be required to diagnose and fix the fault.
At one time you could buy these boards complete, often they are corroded beyond salvage.

Good Luck
TonyS
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nicholas6885
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Re: L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Thu Jun 06, 2013 8:12 pm

Thanks Al and Tony,

I will have a bash at it as soon as I get the time.

I will certainly take a look at what you chaps have said.

I did notice on the Jaguar Classic Parts website diagram, that in the fan unit of these 1994-on systems, there is a fairly standard looking, cube relay that could possibly be stuck on constant battery feed??

I will report back.

Cheers

Nick
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Mon May 19, 2014 5:53 pm

Hello again,
As the summer may... be here again soon,I would like to tackle this fault,as previously posted.

Looking on the Jaguar Classic Spares web page for my 1995 (vin. 195734) V12 6.0 XJS, they no longer list diagram object No. 3 (Blower fan relay).
However,I have seen a relay, for this assembly advertised for the XJS up to 1996 model year(Vin 220000 etc.)and is listed as JLM771,at £26.
Where it gets confusing is ,some sites indicated this part number is only up to 1993 MY??
I have a noticed that this fairly short XJS production run from Nov.1993 to 1996 is throwing-up a lot of supply problems for parts with electrics,headlights and especially front road springs.

Please can anyone tell me if this JLM771 relay will fit my blower motor.
The relay at fault is the L/H one,so is it a differcult job to tackle it from the passenger side?
Kind of hoping that I do not need to take the dash out??
I cant see any link on YouTube to aid me.
Regards
Nick
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby ptjs1 » Mon May 19, 2014 6:56 pm

Nick,

JLM771 is the blower motor relay that was used in a number of models from XJ Series, through XJ40 and both early & late XJSs.

I definitely wouldn't change the relay unless you've actually put a voltmeter on the voltage output pin whilst in situ and confirmed that it has failed and is definitely allowing battery voltage to flow without the ignition.

I agree that there are some parts NLA for the later XJSs but they are still significantly better supported by Jaguar than many other models.

If it is the darlington transistor that has gone, then it's fairly easy to source a suitable one from Maplins or similar.

Good luck

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)

nicholas6885
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Re: L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Mon May 19, 2014 7:25 pm

Paul, Thanks for the quick response.
I have not had time to look under there yet to test the output pin (if I can find it??).
From what you said,maybe its easier then to test it in situ,rather than remove it.
Sort of 85% sure it is the relay. What you said make sense,thanks.
I will let you know what I find.
I guess you answered my first bit ,that this JLM771 relay would fit my car.
Regards
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby ptjs1 » Mon May 19, 2014 7:43 pm

Nick,

Yes, right part number.

In my experience, most auto relays can be slightly lifted whilst still making contact with their terminal slots. So if you look through the wiring diag and confirm the output voltage pin then you should be able to carefully get a test lead to that pin with the relay still in situ.

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)

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poprivet

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Re: L.H Air Con Fan Constant Battery Feed

Postby poprivet » Mon May 19, 2014 8:19 pm

Nick, you proberly have seen a page I wrote many years ago on the subject which can still be found by clicking on:
http://www.jag-lovers.org/xj-s/book/acblower.htm

I really don't know if this is the same as you have but its all I have to go on so I hope I am not providing you with false information. The relay contacts can weld themselves but the result is the fan will run at maximum speed (It is called the high-speed relay because it by-passes the speed control when maximum air flow is required).

Strange that your motor runs slow, unless it is partially siezed. By the way, the relay is inside the fan housing so it all has to come out anyway.

I guess no-one here has had a late model apart, which is how we all have gained this information over the years so if you have confidence you may need to get in there and see what is happening.

As a side note, the Darlingtons rarely fail, it is the diodes that do but while it is apart it makes sense to replace the lot. Oh, and of course, the other side will need doing as well!

Keep us all informed how it goes, it will be of use to many others.

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dhdove
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Re: L.H Air Con Fan Constant Battery Feed

Postby dhdove » Mon May 19, 2014 9:12 pm

"As a side note, the Darlingtons rarely fail, it is the diodes that do but while it is apart it makes sense to replace the lot. Oh, and of course, the other side will need doing as well!"

Well, those electrical things inside the fan box........

TonyS
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Re: L.H Air Con Fan Constant Battery Feed

Postby oldtimer » Mon May 19, 2014 9:13 pm

Hi Nick,
I have read through this thread with great interest - the Delanair A/C system goes back to the 70's XJ's and clearly some fancy electronics have been introduced.

I'm curious to know if you have a wiring diagram for the car and also one for the Delanair system?

nicholas6885
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Re: L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Wed May 21, 2014 11:03 pm

Thanks guys,
The climate control fitted to the 1994-on XJS has the ELMOS system,which was fitted as a more reliable system with fewer components.
Unfortunately,this makes it unique and different with some of the info gained with other models.

I do have the wiring diagram ,taken from the 6.0 part of the workshop manual.

So once I get under there to get to these blower motors,I might get a better understanding.
I think being the L/H one at fault,it is easier than the drivers side .
My car has a passenger air bag fitted,where once there was a glove box,so this could make access tricky and it goes without saying that I must disconnect the battery first.

I will put a post on later for others on how it went and the result.
I much prefer dealing with oily bits!
Bye for now.
Nick
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby PaulGover » Thu May 22, 2014 12:46 pm

"As a side note, the Darlingtons rarely fail, it is the diodes that do but while it is apart it makes sense to replace the lot. Oh, and of course, the other side will need doing as well!"

Well, those electrical things inside the fan box........

TonyS
I've had one certain failed Darlington, and currently (!) suspect its replacement of going short-circuit, as the fan runs continuously. AFAIR, the circuit design meant the original fitments were running very close to their rated maximum. You can now get considerably higher rated replacements of the same shape that should last longer and stand more abuse. There's a discussion already on the forums somewhere.
1981 XJ6 Series III basket case
1991 XJS V12 "facelift"
2008 XJ TDVi

nicholas6885
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Re: L.H Air Con Fan Constant Battery Feed

Postby nicholas6885 » Fri May 01, 2015 5:49 pm

I have finally got around to sorting this L/H fan blower motor out,with a positive result.

In the end,there is not a lot of difference between these Valeo 1993.5 to 1996 fan blowers and the info. already given in this BB about them.

Getting the blower out from my passenger side wasn't too bad ,once the fuse mounting bracket was removed (2x10mm lock nuts) and when I realised that there were two hidden ,top wiring loom brackets attached to the blower !
A word of caution....my late model has a passenger airbag (I do so miss the old glove box) and to aid fan removal,I had to release a horizontal spring loaded,trigger airbag bracket (3x10mm bolts). PLEASE DISCONNECT THE BATTERY FIRST!

I have a fairly average ability with electrics and tend not to test things first and just swap components and hope for the best.
My first hunch (guess) was that the little blue relay(JML771) was at fault,so I changed that.
Yep... you've guessed it....it was not that!

Next to guess ,was the much mentioned,Darlington transistor (Malaysa 2NG284).
Once the pot-rivets were drilled out,I could see the circuit board with nothing looking blown,but noted that this transistor was a little corroded .
I un-soldered it and replaced it with a new Darlington transistor MJ11016 (£3).
The small screws and nuts that hold down the transistor to the board,were rusty,so they were cleaned.
I thought the fault could of been a bad earth etc....as I never tested this transistor?

It now works as it should,but not looking forward to the drivers side ,if that one develops a fault in the future.

As already mentioned,it is a very good idea to test the fan in the foot-wells first and duck-tape the blue rectangle end ducting first,rather than to try to tape it when fitted back up.
I also left the two top wiring loom brackets off,to aid easier removal,if I have to do it again.
I don't think the loom will chafe or move that much.

Looking forward to a cooler cabin in the summer.

I hope this information helps.

Regard

Nick
Nick
XJS 6.0 V12 Coupe 1995

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Re: L.H Air Con Fan Constant Battery Feed

Postby ptjs1 » Fri May 01, 2015 6:04 pm

Nick,

Great to hear that you've fixed it. I have had one fan that won't run on No.1 speed (only 2 & 3) and have been putting off the pulling apart of the Darlington transistors for some time. This has enthused me to get around to it soon.

Also, although disconnecting the battery is general good advice when working on the electrics, it has no link to the airbags, which are completely mechanical in an XJS.

Would be good to see some pics posted if you have any.

Tks

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)


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