Battery drain - cooling fans

[Impman76]

Hello all, sorry to ask a question right out the bat but got an annoying issue with my mk2 pfl octavia 2l tfsi. 

 

I came out one morning and the battery was completely flat, charged it, checked for parasitic loads and alternator output all fine. Used it for a month or so everyday with a 15mile round trip to work everyday. 

 

Got home saturday morning and Sunday morning, kept hearing a car alarm and happened to be mine and battery completely flat again. Charged the battery all day, put it back on this morning and the cooling fans came on full chat. Tried disconnecting and leaving it, still came back on, drove it to work and it was fine for about an hour and the fans were back on again. I've checked the fan wiring plug and it's clean with no moisture. Pulled fusebox out and again no moisture and clean, anyone have any ideas? Thanks all! 

[TheClient]

There's lots of posts on here about this. Challenge is to find them! From memory it is the fan controller, which is integrated with the fans themselves. I'll see if I can search out a thread,...

 

Here is one thread which covers a number of solutions from different contributors. The cheaper options seem to be drying the engine fuse box out, cleaning up contacts to the fan controller, checking fan wiring, external temp sensor.  Beyond that replacement of fans and control unit but expensive by sounds of it...

 

 

Edited 23 September, 2019 by TheClient

[Impman76]

Thanks for  that, much appreciated, fusebox didnt seem damp but it's a free thing to do i guess! I'll give it a go!

[Impman76]

Well I have blow dried the fusebox, not that there was any moisture in it but what the hell. I've also replaced the cooling fan and still have the same issue. Also the alarm went off this morning and the battery was dead flat again. 

[TheClient]

The alarm probably went off as the main battery dead flat.

 

All you can do is really try each of the options that have produced success.  Have you examined wiring and contacts to the fan controller box and cleaned them up?  

 

The most expensive options is going to be changing the fans and controller.  

 

Have you scanned the car with VCDS or had it scanned with a dealer scanner?

[Impman76]

I have changed the fans. I was under the impression the controller was part of the main cooling fan, however when I opened up my old one it was just a motor. Where is the controller located? All plugs to fan and fusebox are in perfect condition. Yeah no codes. 

[TheClient]

My understanding is that it is integrated as a part of the Larger fan assembly.

 

Did you replace the larger fan with a used part?

 

There is also control wire from the engine ECU and if you do some googling at least one post claims that poor contacts and moisture on connectors to the ECU can also cause the fault.

 

There may well be some output testing possible with VCDS to try and confirm fan and controller functionality.

 

 

Edited 30 September, 2019 by TheClient

[Impman76]

Yes larger fan was replaced with a new part. OK thanks I'll look into that next! 

[Lkim13]

On 30/09/2019 at 22:16, Impman76 said:

Yes larger fan was replaced with a new part. OK thanks I'll look into that next! 

Did you ever find out the fault? I'm having similar issues.

[Impman76]

The large cooling fan was one issue and I had another drain which was my aftermarket stereo was drawing current through the can bus, common issue to replace can bus gateway module with a superseded part. 

[Lkim13]

2 hours ago, Impman76 said:

The large cooling fan was one issue and I had another drain which was my aftermarket stereo was drawing current through the can bus, common issue to replace can bus gateway module with a superseded part. 

Thanks for that. I've had the canbus issue too lol but that ones been wired up properly now. Just the fan issue to fix! 

[Impman76]

Easy job too, big fan plug, 4 T30 screws and comes out the bottom, then 3 M6 bolts hold the fan to cowling, job done