Slow speed fan problem - Guide to fixing

Kambo

Active Member
Mar 28, 2013
197
0
Hants
The sleeves are the outside part of the cable i.e red-black, red-white, brown, basically just to identity which colour the cable is, the conductive part is obviously inside the sleeve so you need to very carefully cut just the sleeve and pull both ends apart a little to expose the inner conductive cable, you can get wire stripper pliers for this, splicing just means to get a cable (in this case the resistor cable which has already got one end exposed) and wrap/solder/whatever to the above so you end up with something like a t-piece

It doesn't actually matter if you have snipped the red-black in two as at the end of the day aslong as that wire is hooked up to the resistor wire the end result is still the same

Oh and I'm an electrical newbie aswell so am learning as I go its just I've wrote it out far more complicated than what it is lol I'm useless at explaining straightforward stuff and prefer to do it with pictures which hopefully if I do this next week I will try and get some
 

Crhome

Active Member
Dec 18, 2012
188
0
Nottingham
I had cut red/white cable and connected it to 1 side of the resistor and spliced the other side of the resistor to black/red cable. After I turn my aircon on still nothing, what am I doing wrong here? Only thing I can think of is I have used ledfree solder to do the soldering. Could that be the reason? I hate damn cables and electronics. Can anoyone help??
 

Crhome

Active Member
Dec 18, 2012
188
0
Nottingham
I just thought of something, is there a fuse for fans? Could a fuse be blown out? Could it be because of a fuse its not working after connecting it up correctly?
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
I just thought of something, is there a fuse for fans? Could a fuse be blown out? Could it be because of a fuse its not working after connecting it up correctly?

Don't know about the soldering stuff, I personally would just tie it up and try it out, if its ok then solder or what not

The link that dvance gave above tells you all the stuff you should be checking before/whilst you are sorting out the new resistors, as your there and all that

Top of the battery is a bunch of fuses, the 40amp in the middle is one fuse for a fan, this is my one blown



Part number for 40amp fuse is N 104 249 02, got one from Seat the other day, couple of quid and chance of them having one there to take away is slim

There are also three other 30amp normal fuses, the one closest to the other flat fuses is the 30amp for a fan, not sure which fan but both the above are fan related, check/replace both to start with, if you got an audible multimeter then take the fuse out and run the terminals across to make sure it buzzes up

Like I said in the link above it does show you how to check to see if the fan or whatever is related to them are shot
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
Ok, while I wait for my resistors and stuff to arrive to carry this out I thought I would take a gander at what's what underneath so I don't get any hidden surprises when I do come to do it, not trying to step on anyones toes here or trying to teach people how to suck eggs, the only reason for this is because I've only owned the car a few days so its all new to me and I got a PD150 lump and most of the reading seem for the cupra R with just a mention of if you got a diesel then you need to remove the intercooler pipe, so that's all I was excepting, besides I just like to know what I'm getting myself into

I did this with just a jack and a couple of axles, so unless you're privileged enough to have access to a four poster then there's not much room to work with on your back

First up I took off the engine under cover, I followed cupra-c_ya's handy guide to doing an oil change to remove it but I'm not sure he had a diesel as he had x4 spline T25 bolts and 3 cross head bolts screwed in, mine had x8 T25 spline bolts, the under tray is I'm sure slightly larger aswell, keep the T25 close by as you'll need it

Again I'm not sure how different the diesels are underneath with any ancillary parts but pop out the air filter duct from its housing and swing it out



This is the view from the passenger side wheel, you can see the hole where the duct feeds through, you do need to remove this whole cowling aswell though



There's a few more T25's to take out to remove that cowling and a couple of spring type washers which are all visible



Use a small flat head to prise behind the washer and it should make its way down, if it doesn't then use that flat head to carefully prise up some sections in the middle then go behind and it should move

And out



If you can remove the inner wheel arch (mine were all T25 splines) it will help later, I had a few damaged ones so I had to keep it in place, if you can remove then do so, will help massively later

Once out you can see the fan connector plugs but obviously the lower intercooler pipe is now in the way, view from the passenger wheel again



Wipe a rag down there while your at it, the intercooler pipe comes off exactly the same way as the EGR pipe does topside, if you haven't come across it before then clean up the 'clips' around the ends and put a large flat screwdriver in the recess and turn 90 degrees, the clip will raise slightly so then lever a little more and it should 'ping' into position, you don't take the clip out completely, it will seat itself when its free, then pull out the pipe

While you're here wipe the outside of the pipe and check for any splits/cracks

Once the intercooler pipe is off you can see the fan connector plugs in place, DO NOT cut anything on this side, leave it as it is for now



Pop your head round the other side and look behind it, there should be some convoluted (plastic protective) there, any work/cutting/soldering/testing you need to do is this end



Very carefully cut it down following the lines of the wires, you can easily re-use it with a couple of cable ties once the work is done

You will find the holder that houses both plugs wobbles a bit, just bend it down and it will pop free, there is two small tabs on the side, just gives you more room for the next bit

Any testing you are doing here (thanks to Andy's awesome guide) will be alot easier now, to remove both the plugs for testing you will see they each have two different connections, basically the tab for one is on one plug and the tab for the other is on the housing itself, pop small screwdriver in malarky stuff just like the MAF sensor up top

Getting the radiator fans thermo switch plug off I found was a pain, once that housing above (the one that wobbles) is off you can look directly behind it and see the tab to release it, push this tab in and pull the plug switch off



Because I couldn't remove my inner wheel arch covering I was unable to test the thermo switch itself as I needed a little more room to able to see clearly inside it as the lower rad hose is in the way, also it was getting late and emmerdale was about to start :banned: getting that inner wheel arch off would of gave maybe just enough room, I will tackle that another time, probably with an angle grinder and some happy thoughts :rolleyes:

I know people say there isn't alot of room down there and there isn't really but I've come across worse! I also can't stress enough to be careful when swinging tools or hands, those fans look nice but your hands won't if they suddenly come on, disconnect the battery negative lead and go from there till you need to hook it back up to test etc just remember radio codes, alarm functions etc etc

I tested my fan connector switch and got between .6 and .18 ohms for the red/black terminal, this I believe (from Andy's guide) indicates the fan is ok, however the red/white terminal should be about the same but I wasn't getting a reading atall - zilch, a very high reading indicates a resistor fault, so I'm hoping no reading means that aswell! :whistle:

Hopefully I'll get my resistors through this week to check...
 
I know this sounds stupid but my low speed fans work and the high speed pulses for sort 5-10 secs at a time and it is only in traffic on the motorway it creeps up to between 90 and the 3/4 mark, is the faults stated here relevant to mine?
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
I know this sounds stupid but my low speed fans work and the high speed pulses for sort 5-10 secs at a time and it is only in traffic on the motorway it creeps up to between 90 and the 3/4 mark, is the faults stated here relevant to mine?

You got climate control right? Can you tell the difference between the speeds of the fans whilst inside the car? And when does it pulse, soon after switching the engine on or after a drive?

With a cold engine once you switch on the air-con at idle the fans will move at slow speed, if they are not moving straightaway or are running at the high speed after a couple of minutes then the resistors are shagged

If you want a definite test then you need to get at the fan connector plugs underneath and have a play with a multimeter as per the guide provided in the link above

I'm sure the usual reading is meant to the at the 90 mark so your thermostat could be on the way out and opening later even if your fans are fine, all fun trying to find out :rolleyes:
 
Yeah I have Climate control, the fans pulse after a drive, I noticed the pulsing after a long drive with loads of traffic on the m25 with the temp creeping up, when I got home. It always sits at bang on 90 on a drive and normally idling but does creep after sitting in shite traffic for 20 mins or so.
Thermostat, water pump and temp sensor are all brand new genuine parts, checked the fuse on top of the battery last night and looks to have got hot, but hasn't blown as of yet, but looks like it may now have a high resistance, I am just going to do the resistor mod for both fans and be done with it!

Cheers for your help.
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
Right, I had my stuff arrive through the post so thought I would crack on, again I'm only mentioning this from a diesel perspective as most of the guides are for the LCR

Took out the battery and its holder, OP had used the underside of where this clamps down to hold the resistor plate, I wanted to make sure we have this room aswell





Looks like both engines have the same space available there. I didn't get any angle brackets from b&q/wickes as I had a small sheet of ali sitting here doing nothing, its only 0.5mm thick so its easy to work with, I think you can pick up a sheet from b&q for about £8, measured out what I needed, obviously used the battery holder bolt holes as a template









Finished, view from the passenger wheel



Started engine up and then switched air-con on and both fans started spinning slowly, all good, never had that working before

Took it out for a good motorway drive and got it upto temps then parked up and let it idle but the high speed fans never kicked in, rad top hose was hot but bottom hose was stone cold so will be changing the thermostat and whilst there also the engine coolant temp sensor and thermostatic rad switch all as one

At least the resistor mod is out the way now, some of it was a pain in the behind :whistle:
 
Last edited:

Crhome

Active Member
Dec 18, 2012
188
0
Nottingham
Hey Kambo, glad you got yours sorted mate. Just a quick question. Was your fast speed working before doing this mod? On mine I had only fast speed fans working before doing this mod. And now after doing this mod my fast speed ain't kicking in like yours. Slow speed working. Do you think changing thermostat, temp sensor and rad switch would cure the fast speed problem? If they were faulty, how comes fast speed fans were kicking in before doing this mod?
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
Just to clarify NONE of my fans were working beforehand, start the engine and switch on air-con and no movement from fans, take it on the motorway and come to a standstill and still nothing, temp gauge never went beyond 90

The reason your fans were switching on high speed to start with is because your resistors were burnt out so it was pulsing on the high speed, that is one symptom as per the OP's guide, if your fans now come on slow speed with air-con on with a cold engine that side is fine and shows the resistor mod has worked, like mine I now get slow speed fan movement with a cold engine and air-con on which I never did before

Before I did the resistor mod I did the test with the fan controller switch plug as per the link above and shorted terminals 1 and 2 and the fans started spinning slowly, shorted 2 and 3 with the ignition on and the fans started spinning high speed, so as far as I was concerned my fans were both fine, did the other test with checking for continuity at the terminals in the fan controller plugs and again it showed my fans were fine but resistors were goosed, so did the resistor mod

Whilst there I also changed the thermostat, engine coolant temperature sensor and the radiator fans thermo switch (in the lower part of the radiator) all with main dealer parts, even beforehand with no fans working my temp gauge never went beyond 90, it would take around 10mins of driving for the gauge to get to 90 but never went past so as I was doing the resistor mod I changed all the above

Still the same out on the road after the above changes apart from the only difference my slow speed fan now works with air-con on a cold engine which it never did before which is just down to the resistor mod

So grabbed my old thermostat and old rad thermo switch and put them in boiling water to test



Thermostat started opening once water was boiling and I was also getting continuity on the thermo switch on two terminals so as far I was concerned both these items were working fine beforehand

So I'm at a loss why the high speed fans aren't kicking in, the rad top hose gets hot but bottom hose doesn't even though the thermostat has been replaced but as it turns out there was nothing wrong with the old thermostat anyway but its all been changed now for peace of mind...

Next thing to look at would be the fan control module but I can't see it being that, another thing for some strange reason is the water pump? not sure why I'm thinking that but I know there is an issue with plastic vs steel impellers, my cambelt was done 12k miles ago (previous owner) but not sure if they changed the water pump aswell, I mean why would you trust them even though the book has been stamped with it? might try giving that garage a call to confirm this

So I'm back with the fan control module, if I can grab a cheap one from ebay I'll try that but seeing as this fan problem is a VW thing I would hazard a guess most on the ebay market are goosed anyway! If I can test mine I will

Last thing is maybe checking what the actual coolant temps are, is my gauge correct? is it never going past 90 because its working efficiently? - I'm gonna take that last quote with a pinch of salt though :happy:
 

Kambo

Active Member
Mar 28, 2013
197
0
Hants
Cut it as the brown is the live wire (power) the red/white wire is for the slow speed and the red/black for the high speed, its the slow speed wire which is the problem here, if you don't cut it and just splice into it you are still effectively hooked up to the problematic resistor, you would need to double check this with the electrical eggheads on here but just remember why they ask you to cut it in the first place, also...

...if you have got room to splice you have room to cut, so cut the red/white and hook up the plug end to the resistor and tape up the fan end
 

BoostHard

Complete Plonker
Nov 25, 2012
1,391
1
At Work.......
www.Passionford.com
My parts showed up today, Guess what I'll be doing tomorrow.
I bought far to much heat shrink though, I've got miles and miles of the stuff.

Will post pictures of my progress.




1 question if you don't mind,

I have either 8 Amp cable or 17 Amp cable.
Are either of these suitable as I can't get hold of 10 amp cable



Edit: the resistors are rated at 100w and the 8 Amp cable I have is rated at 105w so I may just get away with that.
 
Last edited:
Dec 29, 2010
1,115
0
Mids
Can I add why do you think the water pump is faulty surely the high speeds was working before hand as you say and not after if the water pump was faulty it would want to overheat causing high speed fans to be on more surely....my low speeds was not working at all not even with air con and my high speeds seems to be pulsate and rather loudly aswell the new fans have now cured my problem... I can get the high speed fans on just by leaving it ticking over for around 30 minutes my liquid gauge shows around 94oc once the fans comes on...


Sent from my iPad using Tapatalk HD
 

Roach

Active Member
Sep 30, 2012
254
1
I'm gonna do this I think, just tried it and my slow speed doesn't come on.

I've only ever heard my fans running at high speed in traffic.

I'll order the resistors through work as they have an account, I'll get more than I need....;)
 
Mar 7, 2011
582
1
Plymouth
Hi,

Just to clarify, should BOTH fans be working when I turn the AC on?

My Smaller fan is working with on the AC button but the larger one is not, also the vents do not get cold.

Any ideas?
 

Crhome

Active Member
Dec 18, 2012
188
0
Nottingham
Yes, both fans should be working after you switch your AC on. With regards to getting no cold air through vents I am as clueless as you. Lets hope someone shines a light into that one for us.
 
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