1.6 engine fans not working

Aaron1.8t

Aaron1.8t

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Hi guys
Changed leaking radiator on a3 1.6 1999... fans dont work and no heat coming out of heaters.. also temp goes past 90 so ive left it it at that.
Ive bled the system... still no heaters and fans..
Could air lock in system cause fans not to work? I thought although temo gauge goes way past 90 the fans would kick in. Or is that because still a blockage and no heaters?

Thanks
Aaron
 
Ok guys quik update. Everything seems to be fine EXCEPT fans dont work so car overheats. Ive tested fans with live feed and they tirned on so guessing wiring,relay issue?
Ive checked fuses ontoo of battery and side panel of dash. All seem fine.
What next? Maybe cts? Fan switch is new..
Thanks
 
If you get no heat from heater, you still have air in your system.
Did you bleed it from highest point? that is usually the heater radiator hoses.
Start car cold and pull one hose off, wait until water comes out, plug it in heater and repeat pulling it out and putting back in until you are certain there is no air. Remember to add coolant regularly so it doesnt take in air.

Fans wont turn if there is air around sensor/switch as it doesnt see the real temperature(air is great insulator)
Does the temperature on system drop at all near 90c? that is when thermostat opens, it should drop a little, if not thermostat might be stuck too.
 
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Fans are switched via the switch in the radiator.... they are also controlled to a degree by the ECU/AC using the fan control unit but ultimately its the fan switch that does the main switching...

If fans are not coming on its almost always the switch being faulty however... as mentioned in other posts if you have an airlock then this will cause an issue...

There should be a drain on the bottom radiator connection... with the engine cold you should remove the cap on the expansion bottle, start the car and let it start to warm up... turn off the AC as this will run the fans at low speed and you really want the engine to warm up quickly... bleed the radiator from the tap a few times replacing the fluid you drain off... this should get rid of trapped air... I would also suggest attaching a short length of hose to the bled tape so as to minimise the risk of getting warm/hot coolant on you...

You will need to monitor coolant temps with VCDS or similar as the gauge will stay at 90 unless temps go way over 100 degrees....

I'd stop bleeding once the temps are above 80 ish degrees... the stat should have started to open by then and you should feel the bottom rad hose get warm... if this hose is not warm then chances are there is still air in the system..

Replace the expansion tank cap... low speed fans should kick in around 96 degrees... high speed is around 105 degrees but as long as they kick in around 96 then all should be good...

You can test if the fans work by unplugging the fan switch and shorting between its 12v feed and the other two connections

<tuffty/>
 
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Hi guys thanks for replys.
Systems been bled and heaters working.
Fans dont work at all even with a/c on..
Fuses all checked so ive ordrd a fan module unit that sits under battery tray..
Lets see if that fixes it.
Will update
Thanks
Aaron
 
(Just something to try if you this happens to you)
I also had a strange fault the fans on my 2000 s3 the fans wouldn’t kick in so I changed the control module under battery & checked fuses. The good news was they worked but only came on constantly if the heater/AC was switched on from inside the cabin. If I did not turn them on manually using the climate control it would cook up.

I found that by unplugging the AC Switch in the engine bay by the firewall although I have no A/C the fans work by themselves and operate as they should.
(Had this same issue on another family members s3 & my previous a3.) just something to try if you get this issue.
 
Last edited:
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I thought the fans failing were a common issue on our cars?
I know when I got my car over 10 years ago, one of the fans was not working and had it replaced and was told it was a fairly common problem.
 
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Ok guys i installed new fan ac module under battery tray and STILL NO FANS... ac fan nor big fans work at all...
What next? Temp goes past 90 after a while.
New fan switch...
Thermostat and cts next
Thanks
 
You need to be systematic...

Need to test the fans at the fan switch 3 pin plug first... one will be 12v and the other two will the fans... test for 12v at the plug... if there is 12v then short from that to one of the other pins... the fan(s) should come on... if not (test both pins) then test the fans at the wiring plug at the bottom of the rad to see if the fans will work there... if not then chances are the fans need replacing...

Typically the fan switch is the culprit... then the fans, then the fan module in that order...

<tuffty/>
 
<tuffty/> said:
You need to be systematic...

Need to test the fans at the fan switch 3 pin plug first... one will be 12v and the other two will the fans... test for 12v at the plug... if there is 12v then short from that to one of the other pins... the fan(s) should come on... if not (test both pins) then test the fans at the wiring plug at the bottom of the rad to see if the fans will work there... if not then chances are the fans need replacing...

Typically the fan switch is the culprit... then the fans, then the fan module in that order...

<tuffty/>
Click to expand...
Ok i need to.get hold of a power tester..

Cheers tuffty
 
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There is a ad on gumtree with some one giving away free yes not a type error but free a few s3 parts. Radiator and fans where on the list if you look you might just be in luck
 
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<tuffty/> said:
You need to be systematic...

Need to test the fans at the fan switch 3 pin plug first... one will be 12v and the other two will the fans... test for 12v at the plug... if there is 12v then short from that to one of the other pins... the fan(s) should come on... if not (test both pins) then test the fans at the wiring plug at the bottom of the rad to see if the fans will work there... if not then chances are the fans need replacing...

Typically the fan switch is the culprit... then the fans, then the fan module in that order...

<tuffty/>
Click to expand...
Hi tuffty,
I tested for live power to both plugs of fans and from fan switch plug and theres no power to it..

So is there one direct area of feed to these 3 plugs i can look into?

I tested fans again with direct feed to battery and both came on so im sure its not the fans.

Thanks
 
Screen Shot 2018 04 22 at 202748


Looking at the circuit diagram it shares a feed with the fan control unit

<tuffty/>
 
<tuffty/> said:
View attachment 153921

Looking at the circuit diagram it shares a feed with the fan control unit

<tuffty/>
Click to expand...
Hi tuffty,
As there was no live feed to fan switch plug, i put a live feed from battery to fan switch live feed wire and fans work.
Do you know where the live fan switch wire leads to... is it to the fuse box inside of car side of dash?
I tried following it but it goes into a harness somewhere into car.
Thank
Aaron
 
Sorry dude... I don't know off hand... would have to trace it through

<tuffty/>
 
<tuffty/> said:
Sorry dude... I don't know off hand... would have to trace it through

<tuffty/>
Click to expand...
Ok thanks...
For now ive just fed a live wire from the 30amp fuse to the fan switch...
Not the best of jobs but it works lol
Thanks
 
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