Fan constantly on, when the battery is connected now

[Chris5044]

Hey guys, so I had an issue with a buzzing fan relay, so I changed that. Next issue is the fan constantly runs with the battery connected now.. So I changed the fan switch and this made no change. So I'm guessing is it the relay again? or the cabling between the 2? Or can it be linked to the fuse box and maybe has water got into the fuse box?

What are your thoughts guys and has anyone else encountered this issue before?

Thanks in advance

[B5NUT]

Could it be a faulty temperature sensor switch on the radiator?

[Tractor Dave]

It's the after run relay that's faulty. It's under the drivers side kick panel. There is a zender diode that blows internally.

[newsh]

I have had strange experiences things happen when I left the top off the fuse box but it's probably the diode in the relay as Dave says. I think these are the details Chris, Dave will confirm.

[Tractor Dave]

Yes, spot on Newsh. I do have a few spare diodes Chris if you are good at soldering

[Chris5044]

Hey thx guys!! Ive ordered the new relay off autodoc and its a different size, but fits.. i fitted it n it worked for a while. Still sometimes heard something.. i still have the old relay.

Ive changed the sensor on the radiator also. Is there another sensor im missing?

Fan Relay (ill double check this)
Temp sensor on radiator..

[Tractor Dave]

As above. It's not the fan relay in the fuss box. It's relay 324 which controls the after run pump and fan when you switch off the ignition. It's located under the steering wheel. Remove the kick panel and it's up there. They are normally brown but sometimes black. I will send you a diode. The relay is nla from Audi and second hand ones are expensive. It's more of a control module than just a relay. Some people just remove them but that's a big risk in my opinion. If you have a really spirited drive, even after letting the engine cool on tick over for a few minutes, the fan and pump will continue to kick in several times for up to ten minutes after switch off. Remember, that after run pump is cooling your turbo!

[Chris5044]

As above. It's not the fan relay in the fuss box. It's relay 324 which controls the after run pump and fan when you switch off the ignition. It's located under the steering wheel. Remove the kick panel and it's up there. They are normally brown but sometimes black. I will send you a diode. The relay is nla from Audi and second hand ones are expensive. It's more of a control module than just a relay. Some people just remove them but that's a big risk in my opinion. If you have a really spirited drive, even after letting the engine cool on tick over for a few minutes, the fan and pump will continue to kick in several times for up to ten minutes after switch off. Remember, that after run pump is cooling your turbo!

oh wow!! thank you so much for all this info!!! id be lost without this!! Thank you.

[Chris5044]

As above. It's not the fan relay in the fuss box. It's relay 324 which controls the after run pump and fan when you switch off the ignition. It's located under the steering wheel. Remove the kick panel and it's up there. They are normally brown but sometimes black. I will send you a diode. The relay is nla from Audi and second hand ones are expensive. It's more of a control module than just a relay. Some people just remove them but that's a big risk in my opinion. If you have a really spirited drive, even after letting the engine cool on tick over for a few minutes, the fan and pump will continue to kick in several times for up to ten minutes after switch off. Remember, that after run pump is cooling your turbo!

Absolute massive thank you Tractor Dave!! for sending me a spare diode!! you sir are a legend!! I will have to strip my part and see if its this diode, but it should be down to the evidence from others and look at getting a pro to do it..

Im thinking about contacting Audi to ask them to support some of their older rare cars - like our beloved s2's... You dont ask you dont get .. and porsche support their old cars.

Thank you dudes

[B5NUT]

Good luck on getting Audi to support the cars. They cannot even perform an oil change on the S2 as the washer for the sump plug is obsolete They don't care, just look how long it took to fix tradition to send parts to the UK after Brexit! I also would not trust any of my local dealers with my S2 and they don't have any of the service information on the cars as it's not listed in ERWIN.

[tango123]

if they got one in for service they’d probably put 0w30 oil in it

[Chris5044]

Good luck on getting Audi to support the cars. They cannot even perform an oil change on the S2 as the washer for the sump plug is obsolete They don't care, just look how long it took to fix tradition to send parts to the UK after Brexit! I also would not trust any of my local dealers with my S2 and they don't have any of the service information on the cars as it's not listed in ERWIN.

[Chris5044]

Hey guys, you never guess what?

I have bought a second hand relay 324.. When I went to fit it today. The previous relay was missing!??? what exactly is going on??
I fitted the relay and the fan immediately came on again with the battery connected. So basically the problem isnt fixed, but I am so baffled now. when was this removed? and how has this car been functioning without the relay all this time??

Does anyone know?

Also maybe the new one is faulty also!??
Is this the guaranteed resulting action from this relay?

Thanks in advance guys

[B5NUT]

Sounds like your car has been messed around with like mine. I had fuses and relays missing. Can you take a picture of your fuse box in the engine bay. Would be interested to see if all the relays are in the correct location.

Also do you know if the relay you purchased is 100% known working? Most sellers say they are but never test them.

[LeoClarke]

Hi! When you say connected battery, do you mean the car battery? If so, the problem may be related to the engine temperature sensor. The temp sensor may be reporting the wrong engine temperature to the engine controller, which will cause the fan to turn on all the time, even if the engine is cold. It is also possible that the problem is related to the fan relay, which may be stuck in the on state due to wear or damage. The cables between the relay and the switch can also cause a problem if they are damaged or not properly connected. If you suspect that water has gotten into the fuse box, this could be the cause of the problem. In that case you need to check the fuse box for damage and corrosion.