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Nice thread! Seems as if I have this issuie too. Been noticing it feeling a little warm the past few weeks in the car, and noticed the fans kicking in at high speed more often. Only saw this thread today - did the test, checked fuses etc., no fans running as they should be at low speed.

My question is, the link that BigAl lists above, is for a 2002 model - mine is a 2001 V6, does anyone know if it will be the same or did they alter it at all because I know some parts changed in 2002.

And theoretically - if I do the fan repair mod above, is that all that I'll need to get it fixed? Is there anything else to try first?

Thanks - and thanks for the posts above - huge thread and not read all of it! But good and informative
 

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Nice thread! Seems as if I have this issuie too. Been noticing it feeling a little warm the past few weeks in the car, and noticed the fans kicking in at high speed more often. Only saw this thread today - did the test, checked fuses etc., no fans running as they should be at low speed.

My question is, the link that BigAl lists above, is for a 2002 model - mine is a 2001 V6, does anyone know if it will be the same or did they alter it at all because I know some parts changed in 2002.

And theoretically - if I do the fan repair mod above, is that all that I'll need to get it fixed? Is there anything else to try first?

Thanks - and thanks for the posts above - huge thread and not read all of it! But good and informative
I have a 2001 v6 and used this kit.Had exactly the same issues as you its now fine.
 

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A few mnths ago i had a problem with my 2001 V5 170 bhp,every now and then my temp gauge would go of the scale and the only way to get it back to normal was turn of the heater completely or turn the engine off. After scanning hundreds of forums,DIY pages and know all sites i found this topic,took the time to sort of read it and had a go at the fix!!

Sorted,works a treat,fans working again,temp as it should be(think my MPG went up a bit aswell)

Cheers andymac and BigAl

pic of fix here

http://uk-mkivs.net/gallery/album/33946-fan-fix/

Again thanx
 

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Problems with your fans READ ALL OF THIS then comment...
Results of the fan poll here, left this running long enough, and now the thread is too long too read so I will cut it down here along with the results, also it should be able to be made sticky!!!
here is the original http://www.uk-mkivs.net/forums/1/209822/ShowPost.aspx#209822
The Total was over 45% of fans were or have been faulty
BELOW I WILL COPY THE USEFULL REPLYS TO THAT POST (along with an acknowledgement)

ANDYMAC: Right I will explain this only once as I have explained it SOOOO many times over the last year
Basically all cars with climatronic have 2 fans and each fan has 2 speeds, slow and fast.
When the air con is on the fans are meant to turn at a consistent low speed and if the engine gets hot they will run at the higher speed, but what is happeneng to almost all fans is that the low speed resistor within the fans is burning out so the fans will only pulse to high speed which isnt really adequate for cooling the engine in warm weather, another consequence is that the high speed fuse blows and you are left with no fans and overheat and bugger your engine.

I have so far dissasembled 3 sets of fans and all had the same problem, which was the low speed resistor, the fans are a sealed unit so cannot be easily repaired, VW charge �90 + VAT for these EACH and �200 labour for fitment, so basicallly you have �400 concumables on your car that need replacing every 30000 miles, which in my eyes is very very wrong, if nothing else they should be supplying them on an exchange basis as per the MAF as it is such a widespread problem, I have even heard of R32's with the problem now. I f I can get enough support on here plus one or 2 people who have had a run in with VW about this then I am going to approach watchdog as it is disgracefull that VW are profiteering of a known engineering problem on one of the models.

ANDYMAC: I looked at over 6 4motions last year for my mate, and every single one had this problem, I would hazard a gueass that many r32's are now having this problem aswell, however the it does affect all models I think not just V6ers and V5ers

ANDYMAC: right I need to clarify this as some people arent getting this
1. turn engine on,
2. turn aircon on,
3. make sure ECON is "OFF"
4. Check fans are running constantly IE for more than 1-2 minutes
5. if the fans do nothing then run very fast, then stop after a minute or 2 or even 3 then you have faulty fans

BIGAL: The radiator fans are controlled by a two stage thermostatic switch, the first switch closes at approx 85 degC and switches on the low speed fan and the second closes at approx 95degC and runs the fans at full speed. I assume this two speed arrangement is to keep noise levels down, as the fans never need to run at full speed under normal circumstances.
They come on low speed when the aircon is on, to cool the aircon compressor which is mounted directly behind them.

BARON VON MARLON/RF STEEL: Baron Von Marlon - If you've had your fans replaced once already, they should still be under the 24 month warranty that comes with the replacement !!
Replacement Parts. All genuine Volkswagen replacement parts purchased on or after 01/11/01 carry a warranty for a minimum period of 24 months, with no mileage limitation, from the date of purchase. Parts replaced within the warranty period for passenger cars are covered for the balance of the 3-year period. After this period, replacement parts carry the 24-month warranty referred to above. Other items with warranties in excess of 24 months will be advised to you at the time of purchase. This does not apply to parts fitted under the terms of the vehicle warranty, which are warranted for the remaining period of that warranty.
http://www.vw.co.uk/services/factory_warranty/terms

ANDYMAC: Origianl Fan Autopsy here http://www.uk-mkivs.net/forums/17772/ShowPost.aspx
Do not use fix shown here it doesnt last long!!!

BIGAL: My fix is more straightforward, it only involves mounting two resistors on to a metal plate and splicing into the fan wiring. It does not involve any disassembly of the car (especially the fans) and does not damage the cars wiring loom. The only hassle is making the metal heatsink plate, it is only approx 30 mins work for anyone with simple metalworking tools. I have drawn up the heatsink and can email the drawing to anyone interested.

BIGAL: From Thread http://www.uk-mkivs.net/forums/50268/ShowPost.aspx
I checked my V5's cooling fans today and they are no longer running on the low speed. I've disconnected them and checked the fans by themselves and the internal resistors are burnt out on both fans.
I have reread the posts by Andymac and others about this problem and I have decided to fit external resistors to repair the low speed function.
From Andymacs previous posts it looks as if the resistor for the bigger of the two fans is approx 0.8ohm.
I have just tried a 1 ohm high power resistor in series with each fan and measured a current of 7.0A (with engine running) for the big fan and 5.5A for the small fan. This means that the big fan will need a minimum of a 50W resistor and the small fan a 30W resistor.
My question is, has anyone actually measured the low speed current drawn by each of the fans when running with the internal (unbroken) resistor? If not does anyone know the internal resistor values for both sizes of fan?
I will publish details of this mod when I have finished it.

JONJON/ANDYMAC:Quote: posted by JonJon on 09/04/2005 19:46:12
i'm also intrested in this as my slow speed fans are not working.
it's not causing any bother though as the temp needle never moves over the 90 mark,even if i just let it idle til the high speed fans cut in,is this normal(in a broken sort of sense)i.e what temp is the fast cut in supposed to be?
BigAl- if it's not too much bother could you explain how you tested the low speed supply to the fans so i can check mine.
The temp needle is very inaccurate! believe me the car will be running at higher than 90, the other problem is when you get stuck in traffic on a hot day the high speed will blow a fuse then you will be left with no fans and you WILL overheat. PPS no low speed will also bugger the aircon compressor and lead to a a �1000 bill, (Ask RFSTEEL)if you dont fix it soon at least take the following precautions carryu a spare fuse with and the tools to change it and run the climatronic only in ECON mode.

BIGAL: (The fix)I have been setting up my webspace to host this guide, hopefully it will be finished shortly, it will be viewable at http://website.lineone.net/~alan.james.lorely/
Andy, both resistors are on one heatsink which is mounted under the passenger side headlamp. It is not in the fan airflow and doesn't need to be provided the heatsink is the same or larger than mine. I tapped into the wiring on the fan side of the wiring, this means if anyone want to replace the fans later and remove the mod then the cars wiring is undamaged.

BIGAL: The failure of the fans low speed does not directly damage the engine, but the constant high speed pulsing of the fans does eventually blow the main fuse and then engine overheating could occur, which if ignored would lead to engine damge.
The air con compressor is mounted directly behind the smaller fan in the airflow and I believe that this is to cool the compressor, presumably lack of cooling damages the compressor.

TIW30: Just finished my resistor mod (Thanks to Big Al for all the research) and both fans are now working perfectly all for �15 great the mod is quite straight forward if a little fiddly to do in some places, and anyone doing it in a 150 TDI will need to remove the front intercooler pipe to get access to the plugs

BIGAL FIX: http://website.lineone.net/~alan.james.lorely/fan%20mod/Repair.html

Dsgwagen: (numpty) A lot of the time problems with the fans are caused by the control unit,if you change the fans and the control unit is faulty they will go again.

ANDYMAC:Its got nothing to do with the control unit, if it was how come 03 r32's with the r32's are suffering the same problem.
Dsgwagen do you care to explain where and how the control unit creates a problem? have you read the whole of this thread? have looked at the links or worked out the current calculations that the thermal resistors within thae fans have to control? how many fans and control units have you replaced or diassembled?
I am asking this as at the end of 10 pages of thread and investigation by myself and a few others such as BigAl you jump on and say its the control unit? I just want to know on what eveidence you base this on.

NUMPTY: I was under the impression that the control unit fails causing the fans to get stuck on fast blowing them out usually taking the 40a fuse with them.I can't really be bothered to read the thread or the 10 elsewhere but i'm just pointing out that a lot of control units get sold,maybe for a different fault to the one you are highlighting but still.

ANDYMAC: Well if you cant be bothered then dont clutter the thread with untruths, and uninformed advice, I already spend half my time reassuring people that ITS NOT THE CONTROL UNIT mostly because people like you DONT READ THE EVIDENCE AND ASSUME ITS SOMETHING ELSE

ANDYMAC: IF YOU READ THE THREAD THE 40 A FUSE BLOWS BECAUSE THE FANS ARE PULSING WAY TOO MUCH ATTEMPTING TO COOL THE ENGINE, UNSUCCESSFULLY BECAUSE THE LOW SPEED IS BROKEN!!!!!

DSGWAGEN: I was told that when this problem first came about that they were just changing fans and they were going again,but now they change the lot 2x fans 1x ecu and the fuse and they don't get any comebacks now.

EVILHOMER: Dealers LIE!!!! lol

ANDYMAC:
I have done the resistor mod and it works fine, howver you do need a fairly substantial piece of aluminuim as they do get exceptionally hot (Still going 10000 miles on)

GREENBEAST: right...i got my fans working again
i implore anybody about to undertake this mod to check the green fuses on top of the battery and clean them up so they are free of corrosion
my father-in-law-to-be and i only discovered they were corroded AFTER we had fitted the whole resistor modification
so after the fuses were cleaned up it all works and we've reconnected all the wires how they originally were
only good thing is that i have a ready made resistor mod for if/when the fans do go properly!

ROYR32: My R32 went in for warranty work and we asked them to check the fan as it only comes on high speed for 3 - 4 seconds. When we picked it up the man told us that they had spoken to VW and they said it was within acceptable peramiters. It did it in front of a couple of the "technicians" and we told them that was what we talking about. I said I could not see that it could do anything during that short period. He said it does, because it is such a high speed fan it only needs that long! Is this faulty or could he be telling the truth?

ANDYMAC: I can confirm that your fans have failed, and Roy read the whole rthread and realise that yours have failed and dealers are liars and are stupid

RHEMINGWAY:GET YOUR ALI PLATE HERE!
I did the external resistor mod last weekend and they work a treat.
A mate in the metal industry, laser cut a piece of 3mm ali using the template on Big Al's site. I followed all the instructions on his site so thanks a lot Big Al, you saved me a fortune and the template was spot on.
This shape fits fine on V5, V6 cars (thats what Big Al had) and I have a 150tdi so assume it would fit all the TDI's.
If anyone wants a plate laser cutting then I can get them for �13 each, but the minimum order is 10 pieces. If anyone wants one then send me a pm or maybe reply here, I could set up a group buy if enough interest. I am not making any profit on this, its cost so if anyone can get it done cheaper then thats cool.
Hopefully there should be a pic attached.
Fanfix0002.jpg

Rich

RHEMINGWAY FIX GROUPBUY: http://www.uk-mkivs.net/forums/371240/ShowPost.aspx

ADDED EXTRA TESTING Courtesy of BIGAL AGAIN...

First the fans themselves.
Disconnect the fan connector and measure, with a multimeter, the resistance between the red/white wire and the brown wire, it should be a value less than 10ohms, a much higher value indicates a burnt out internal resistor. Next measure the resistance between the red/black wire and the brown wire it should also be a value less than 10 ohms, a much higher value indicates a burnt out fan.

Next the fan controller, fuses etc.

The test detailed is taken from the VW repair manual for the V5.
Caution keep hands etc away from the fans during this test as they are expected to run:

Reconnect both fan connectors, if still disconnected, and disconnect the 3 pin connector from the radiator fan thermo switch.
Bridge contact 1 and contact 2 with a short piece of wire, the fans should run at low speed.
Switch on ignition, bridge contact 2 and contact 3 with a short piece of wire, the fans should run at high speed.
Switch off ignition, reconnect thermo switch connector.

To identify the connector pin numbers, hold the connector facing you with connector latching mechanism at 2 o'clock, pin1 is then at 12 o'clock, pin 2 at 4 o'clock and pin 3 at 8 o'clock.

For anyone who wishes to try to test the thermo switch, low speed is switched on between 92 and 97 degC and the high speed switches between 99 and 105 degC.

ADDED (NEW FANS 15/May/2006)

The newer fans will fail some guys on here have been through 4 sets ... even some of the last R32's on 54 plates have had fans fail...... the most common PM I get is will the modded fans ... my answer is yes but not quite as quickly as the originals, I have seen some original fans fail in 15k and modified ones fail by 40k but this hard to verify as it is hard to know if they were fitted from new... but they still failed.

The reason they will fail is a design fault of VW all other cars from the big Audis down to the P()assats with climatronic, use a fan speed controller, that utilises "pulse width modulation" to control the fans and thus negates the need for resistors in a high current circuit. (I have been told this by several reliable source but dont know if its the gospel truth)

Now should you fit them? well my opinion is this

  • if its warranty job yes, as it keeps the car oem (but inferior LOL) but costs VW in the region of �500... serves emm right
  • if its not warranty, well its your choice �400 for something inferior that will fail half as fast as a clutch! or �15 and 2 hours work for a fix that will outlast the car!!!!

THATS ALL FOLKS....... the longest synopsis ever.... but it should stop any stupid questions about fans or is it really the fan.
 

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Cheers imageworx that's the answer I was looking for,heard about wiring em threw a caddy Tdi resistor but this option seems more straight forward as it's proving difficult to find info on the caddy option. Mod, fix sorry new to this forum malarkey
 

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ANDYMAC: right I need to clarify this as some people arent getting this
1. turn engine on,
2. turn aircon on,
3. make sure ECON is "OFF"
4. Check fans are running constantly IE for more than 1-2 minutes
5. if the fans do nothing then run very fast, then stop after a minute or 2 or even 3 then you have faulty fans

My fans exhibit a different problem(?). With aircon on both fans run fast continuously from cold, they do not cycle on/off. WIth aircon off, the fans don't run at all. I don't seem to have slow fan operation. It is difficult to know if I have a problem from your description above.

What you've done here is describe the symptoms of one possible failure yet others have different symtons. It would make more sense to describe the correct operation of the fans, both with aircon on and off. Doing so would allow others to more easily identify if they have a problem or not. Can you do this?

Since the two fans have separate purposes (one is to cool the radiator, the other cools the aircon condenser) I would expect any description of their correct operation to explain how each is affected by the aircon being on or off.
 

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Looks like ill be doing this at the weekend. Temp gauge has been hunting between 90-100 degrees in traffic in hot weather and my low speed fan doesnt work with climatronic AC turned on. This has been bugging me for weeks!

For those that need it, you can find the resistors here - http://uk.rs-online.com/web/p/panel-mount-fixed-resistors/0188087/
Yowsa!!!! You just can't beat a thread with big manly 100 watt resistors in it! None of this namby pamby stance rubbish here! :p
 

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Finally got round to doing this today. Thanks to those who put the info up :Y:

It was a little bit of a ballache I'll be honest, but only because I was working from the driveway and didn't have much room...plus the wires didn't have much slack. For future reference, do the fan connectors come out of their housing? I had a go at pulling them out but they were tight as a nuns chuff, so didn't want to ewnd up snapping them
 

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Just had a read thru some of this and need a wee bit advice.

I bought my v6 4mo last year and all has been great until now. The fans have stopped working, I ve not had a chance to test them yet, the previous owner had already done the ressistor mod. I ve just changed the control module control module as I was advised by a friend before doing my research. Still no joy.

This afternoon I found that the 30a fuse on top of the battery was melted.

Just wanting to see if anyone else has had long term issues or could it just be my fuse?
 

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Just had a read thru some of this and need a wee bit advice.

I bought my v6 4mo last year and all has been great until now. The fans have stopped working, I ve not had a chance to test them yet, the previous owner had already done the ressistor mod. I ve just changed the control module control module as I was advised by a friend before doing my research. Still no joy.

This afternoon I found that the 30a fuse on top of the battery was melted.

Just wanting to see if anyone else has had long term issues or could it just be my fuse?
Those fuses always melt in the end,a new fuse box and you'll be sorted for the time you own the car.
 

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Hi guys,just done the resistor fix on my mk4 gti.
They worked fine the first time I started the car.jumped in it yesterday to go for a blast,turned the ignition on and the fans came on. On inspection I noticed the fuse box on top the battery had melted the green fan fuse to the box. Can anyone shed some light on the matter?
Thanks
 

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Hi guys,just done the resistor fix on my mk4 gti.
They worked fine the first time I started the car.jumped in it yesterday to go for a blast,turned the ignition on and the fans came on. On inspection I noticed the fuse box on top the battery had melted the green fan fuse to the box. Can anyone shed some light on the matter?
Thanks
They all do it sometime in the life of a mk.4.It'll need a new fusebox at the very least.
 

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Hi all I've had no fans at all and no air con (climatronic) since buying my golf. Done the ignition off/on slow speed high speed checks and I get no fan operation at all. I've got the car upto temperature and let it idle till the temperature was at 92 degrees and no fan kicked in. I've inspected the fuses above the battery and he all look good and no melting of the plastic base. I have checked all the fuses with a multi meter and all are getting power.
I've done the check with a jumper cable at the thermo switch connector and both fans powered up on slow speed and high speed when the terminals were bridged. I have swapped the Fan Control Module with another used one to see if it was the FCM and still no change. It was a used FCM though but was assured it was working. I've put a multi meter to the terminals on the connector and one of them showed just over 12v so I know the FCM is getting power.
Anyone have any ideas? I have no fans at all but they work when the terminals are bridged. And I have no air con. It blows but no cold air
 
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