# Audi TT radiator fans not working



## Trappers (Jun 14, 2014)

Hello 

So i've done a lot of research on the audi tt radiator fan issues. There's clearly an issue with the way these fans were designed to function, however i am going to attempt to fix mine.

2003 Audi TT 1.8T 

The symptoms are as follows:
Both fans only operate on high speed.
Both fans only operate when AC is on.
No after run fans. 
Fans cycle on high speed for a few seconds on and off.
not overheating, AC works fine.

Both fans were replaced about 3 years ago. I first noticed the fans were acting up again when my AC became warm and my car started overheating. It ended up that the metal fuse on top of the battery had blown. I replaced that and now i have the symptoms listed above. All other fuses elated to the fans have been checked. I recently replaced the large fan and both fans would run on low speed when the AC was on but would continue not to operate without AC on. 

After looking at a ton of different posts online about these fans, this is my understanding of how they sort of function.

I believe the low speed is mainly engaged by the fan switch located in the side of the radiator.
Therefore, i have a feeling there's an issue with the coolant at that location or the switch itself. 
The AC will turn on the fans using the fan relay module under the battery when the AC is on, but since the low speed doesn't work the high speed function gets cycled on and off.
I'm worried my fans low speed may be burnt out as the new large fan caused both fans to work on low speed when the AC was on but only after 3 weeks they do not run on low speed anymore.
I also notice that the coolant hoses at the top of the radiator are very hot and the hoses at the bottom (near the fan switch) are very cool. If the radiator is plugged, not much water will be making it through, and if the plug is anywhere around the coolant fan switch, then it is preventing hot water from getting to the switch itself.

So my first step is going to be getting a new fan switch and ill connect it to the clip and heat it with a lighter while the cars on to see if i can even get the low speed to operate. I have a strong feeling my radiator is clogged. If it is, does anyone have any advice to unclog it? or am i looking at getting a new radiator? Also considering flushing the system and changing out switch, thermostat and temp sensor all at once. Might as well replace the fan relay module too. 

also, ive seen mentioned that pulling fuse 16 should cause the fans to come on but that does not happen for me. 

I really want my fans operating the way they were meant to including after run. If anyone has any advice or experience with this issue, any assistance is greatly appreciated. Thanks!


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## TheDeckMan (Sep 26, 2004)

Sounds like a bad FCM.


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## esoxlucios (Sep 17, 2009)

How was this resolved?


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## waih136 (Sep 13, 2014)

Ever figure this out? i'm having the same problem except i don't have high only low.


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## Trappers (Jun 14, 2014)

So i'm still trying to figure this issue out. I ended up replacing the radiator coolant temperature sensor, the fan switch sensor in the side of the radiator and flushing the radiator. Then I replaced the large fan and the fan relay (located under battery). I'll add a more detailed comment later with part numbers and so forth. So anyways the fans both start working, but still no after-run and only with AC on. Then after about a week fans go dead. I bust open the relay and sure enough the thing MELTED. I'll add pics later. Something is causing these fans too draw way too much current. So I replace the relay and the fans will only work on high speed again. I bust open the large fan and sure enough the slow speed resistor has blown (irreplaceable BTW). The resistor in the fan is a little metal coil. I'll upload pics of that later too. Soooo now i'm kind of lost as I don't have much experience with electrical. I'm having a buddy who works on VW's come look at it, who also happens to be an electrical engineer. I have ordered 2 additional fan relays and new fans (both small and large). Hoping that replacing both fans and the relay all together will do the trick as I think both my fans are busted and drawing too much voltage/current. Anybody with any electrical knowledge, please feel free to provide feedback. I should get my parts within the next 2 weeks and will have my buddy help me try to figure out the issue. I'll post updates as this progresses. My plan now is just to get the cooling system working and sell this POS car, as I'm sick of dealing with it. I know these fans are a huge issue for this car as the internet Is full of people with similar situations.


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## lite1979 (Sep 9, 2005)

Check the fuse tray on top of the battery. Even if all the fuses look good, the fuse block itself is prone to melting and causing short circuits or open circuits.


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## Trappers (Jun 14, 2014)

good idea. I'll check it tonight. I have had to replace the 30A fuse link before. The one that goes to the fans. So something could possibly be going on up there.


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## Trappers (Jun 14, 2014)

sorry for updating this so irregularly, but I have been driving my other car and have been working on the audi TT when I find time. So I finally fixed the POS. I couldn't get the fans to operate correctly and I knew there was too much current/voltage going thru the system as I have gone thru 3 fan relays. I'll post the pics soon. All 3 melted. So I finally decided to take both fans out and the large fan I had previously replaced was fine and the smaller fan had in fact melted (the resistor in the fan motor melted). I replaced the smaller fan, so now both fans are new and put in a new fan relay and what do you know! the fans are running perfectly on low speed and even get after run fans after a longer drive. What a relief! I thought I was gonna have to pay someone to fix it. 

Anyways, if you have an issue with your radiator fans, I would first check the fan motors themselves as these fans have small porcelain covered resistors in the motors that tend to melt after a lot of use. This is my 3rd set of fans. The 2nd set came under warranty a while back. I've read online there's been a huge issue with these from multiple VW/Audi owners of these 1.8T engines. 

I'll also post pics of my melted fans so you can see what i'm talking about. Don't be afraid to open the fans up. They're easy to take apart and re-assemble. Just pry the back plate off with a flathead screw driver and there's only like 3 main parts in the fan motor. If you see melted plastic you'll know right away the fan is useless. I thought about replacing the resistor in the fan but they're a very hard to find type of resistor, just a wavy looking piece of metal covered in a porcelain type sleeve. Plus if the plastic housing melts you'll have a shorted circuit anyways. 

From my experience the resistors in the fans melt and then the relay melts. The fuse on top of the battery should protect this but it doesn't, So if you have fans that aren't working just order 2 new fans and a relay, I got all 3 from ECS for $150. I just used the URO brand or maybe MRC brand, can't remember, but these fans are like $200 a piece if you get the audi ones and they all fail just the same, so why pay more. 

If anyone needs help with this just post in here and i'll check back every once in a while.

I've done a coolant flush, replaced the coolant reservoir, thermostat, fan switch, temp sensor, coolant flanges and hoses, fan relay box, radiator fans, fuses on top of battery, power steering pressure switch, and performed multiple oil changes. The hardest thing to do is the stupid thermostat.. it's buried under a nest of breather hoses and very hard to get to. I used two knuckles on a socket wrench in order to get to it. 

I guess I should mention the removal process of the fans just in case someone's interested. In order to take out the fans you'll need a 10mm socket, 13mm socket and I think a 25 star shaped screwdriver. I think they call them T20 T25 and so on. I just have socket with the T25 on it. So first you need to jack the car up enough to pull the fans out from underneath it. Then take out the black pipe that is underneath the fans, I think it's called the intercooler pipe, it has 3 13mm bolts on each side of it and 3 10mm nuts holding the power steering lines to it. So first dethatch the power steering lines and then the 13mm bolts and slide that pipe out. While your down there disconnect the fan wires from the wires that lead to the fan relay (under the battery). Also disconnect the battery if you would like. Then detach the electric water pump that's connected to the fan shroud using the T25, there's two screws. Then disconnect the fan shroud, there's four T25 screws. one in each corner so to speak. Then get under the car and pull the fan shroud out with both fans attached to it. You'll have to push the lower coolant hose back out of the way. Then there's 3 10mm nuts holding the fans to the shroud. Disconnect those and you can take apart the fans if you would like. When you replace the fans with Non-audi fans you might need to shave out a small area on the fan shroud for the wiring as the audi fan wires come out on top and the non-audi fans come from the side of the motor. If you own a power drill, just drill out a small hole for the wires in the side of the fan shroud, just don't damage the integrity of the shroud, the wires are small and you only need to shave off a small amount of plastic. Install the fans back into the shroud and I connected them to the car before installing them to test them while I had them out. Once things checked out I re-installed them. again if any one has any questions, just message me or post in here and i'll check back. 

Thanks!


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## sciroccohal (May 4, 2005)

*40 year old trick*

So my first step is going to be getting a new fan switch and ill connect it to the clip and heat it with a lighter while the cars on to see if i can even get the low speed to operate. I have a strong feeling my radiator is clogged. If it is, does anyone have any advice to unclog it? or am i looking at getting a new radiator? Also considering flushing the system and changing out switch, thermostat and temp sensor all at once. Might as well replace the fan relay module too. 


Remove fan switch after draining coolant.
READ the fan switch temp on side of fan switch.
Place in pan of water on stove just up to the brass nut...not over!
Attach OHM meter on 'continuity beep' to both terminals.
Put a 0-265 degree meat/candy etc thermometer in the water and slowly bring up to temp.

Click------BEEEEEP
check all the terminals...three I believe.

Does that temp match the rating of the switch?
Does it ' un-make' as the temp goes down?

They've been making the same dang switch since 1974.

Check all fan switch grounds.

good luck.


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