Both Radiator Fans Staying On Constantly.

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robarthur

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Hi guys,

My girlfriend returned to her car after work and noticed the fans on. so thats 8 hours since she started. she dropped by at my work where i have had a look. both fans are staying on, ive read other posts and its normally only one or the other. couldnt locate the radiator fan switch to try that, so ended up just disconnecting the power to the fans at the bottom of the rad so she could drive home and turn the car off without draining the battery.

Could you guys give me any advice on the situation? also where is the fan switch located? Hoping its not going to need whole new fan assembly if thats the cause :(

Thanks

Rob
 
Various issues can cause that problem.

We're the fans on slow or fast? (fast is pretty loud and can be heard from outside the car).
 
I wouldn't have said they were on full speed. I could hear them with the bonnet closed but not to bad.
 
There is no "fan switch" as such, there are two coolant temp sensors, if one of these has gone then it could be the cause.

The fan controller is built into the large fan, this has a habit of failing and causing them to stay on, usually on full speed though. I'd get it scanned for faults first, to check what the car thinks is going on, if none are reported I would use VCDS to look at what the coolant temp sensors are reporting, if they are normal then I would look at the fans.

Coolant temp sensors are about a tenner, fan packs are about £350 new or £75 from a breakers.
 
im guessing one sensor is on the block? and one on the end of the rad somehwere? do you know if you can view both sensors individually on vag-com? i havent had to log or view the blocks in a while. hopefully i can scan her car in later this evening as im work again. is it worth getting a second hand one at all? and is it possible to take the controller out of the fan and repair it? we have some pretty handy electrcians at work both auto and commerical shall we say. maybe they could replace/fix it after i have sourced a used set?
 
I've only ever replaced one of the sensors and it is in a coolant pipe on the side of the block.

When I had a similar problem I just replaced the fan set in it's entirety, cost £75 quid from a breakers and came out of a 2009 Passat. I couldn't tell you if the controller is repairable, as I didn't try, I drove for too long with the fans on full speed and they ended up burning out.
 
ok i will check that tonight, will get a meter on it as well to check the readings to. just looking at etka how come they list the fans seperate on the system yet apparently you can only but the whole lot? as for your fitting one from a passat, im guessing that was for your a4 in your sig pic.

so im guessing that a fan setup from a mk5 golf for example would also fit? will have to do some digging through etka
 
It's an A3 in my pic, funny angle lol. The fans are in a variety of cars, golfs/passats/octavias/tourans.

I was confused when I looked at etka too, because the parts are listed separately, yet nowhere sells them like that.

Just make sure you either get the right part number, or remove the fans first to compare to whichever ones you buy. I tried a set from a 1.9TDI A3 and although very similar, didn't fit my 2.0TDI.
 
thanks for the info ill have a quick search now for used ones just incase. prime myself up for the worst. last year of the misses owning her a3 has been costly to say the least.
 
well managed to find one on the bay which is correct for 65 quid so if turns out to be that ive saved myself some dough.
thanks for the info and advice so far
 
bit of an update, only today have i had the chance to have a look at the girlfriends car. i've scanned the car with vag com and came back with one fault code which is below

VAG-COM Version: Release 409.1-S

Control Module Part Number: 03G 906 016 G
Component and/or Version: R4 2,0L EDC 0000SG 5334
Software Coding: 0000072
Work Shop Code: WSC 06435
1 Fault Found:
18080 - Coolant Fan Control 1: Open or Short to Ground
P1672 - 000 - -


i did try both temp sensors disconnected and when connecting the power supply to the fans they came straight back on. ive tried to search for the fault code on ross-tech wiki but it doesnt appear on there at all. having a quick search ive seen people mention the fan control module. is this located under the battery?
 
On mine it is inside the fan itself I believe. Not sure on others, mine is a BKD engine, what is in yours?
 
I did think it was in the fan. Just kind of thought otherwise when reading a few posts elsewhere. Also with the 1.9tdi fans you tried how were they different? As the part numbers are identical apart from the letter at the end of it?
 
The fans from the 1.9 i tried had the bolt holes in different places, and were a tiny bit smaller if i remember correctly.

The correct fans will have for rubber flaps in one of the top corners, the 1.9 ones didn't.

If I were you I'd buy a set of fans from a breakers yard and just swap them out. Just bear in mind they have to come out from underneath, they don't fit if you try and take them out the top.
 
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