2006 mk5 both fans only work when engine is off

john_tsouris@hotmail.com · May 22nd, 2012, 11:08

Arrrrrgh! VW and their electrical systems!

I have a 2006 tdi and both cooling fans will come on when the ignition is on but the engine is not.

Start the engine, turn the ac on, and the fans will not come on.

Since this model also has a problem where the fans will not work in limp mode, destroying the ac compressor, I'm thinking of just hard wiring the fans to the ignition forever and calling it a day unless someone can tell me why that would be really, really bad.....

Henrick · May 22nd, 2012, 13:05

I'd suggest talking to Dan (DanG144 I think is his screen name here). As far as I have read his posts regarding A/C and fan issues, I've made a strong impession that he's the A/C and fan guru. He knows these things best. And his troubleshooting steps were really useful/helpful.

nord · May 23rd, 2012, 05:07

I'd suggest acquiring a wiring diagram rather than just guessing. If I were to guess though, I'd opine that there are two distinct electrical paths to those fans. The primary path existing while the ignition is on and the secondary with the ignition off. The secondary path existing to assure a proper cool down after the car has been parked after use.

Given that your fans do work I'd have to assume there is no problem from that standpoint. The same for the temp sensor as it's a common component in both cases. The key here is the engine. Somewhere there's a component that changes state with the engine running.

Knowing what I do about VW, their engineering, and the typical German mindset, I'd be looking at either a solid state or mechanical transfer device. The cheapest and most reliable being a simple relay... Then again, German logic is sometimes neither simple nor logical.

whitedog · May 23rd, 2012, 05:40

HERE is a link to Dan's thread.

My guess is the fan control module isn't working right, but that's just a wild guess.

Ol'Rattler · May 25th, 2012, 13:53

Quote:

Originally Posted by whitedog

HERE is a link to Dan's thread.

My guess is the fan control module isn't working right, but that's just a wild guess.

I would "guess" that as well. I would also "guess" that the A/C system isn't sending an ON command to the fan controller.

Before I did anything, I would do some troubleshooting with VCDS first to get an idea of what is actually happening.

john_tsouris@hotmail.com · May 25th, 2012, 14:10

Obviously the controller isn't turning on the fans.

I had this at the stealership and they "forgot" to look at it.

I do not own a Vagcom. Everytime I search for one there are 50 to choose from and I know not what the hell to buy.

Regardless, I'm not replacing the fan controller even if it is bad. It probably should be removed, stuffed with copious amounts of black powder and detonated. This fan controller has destroyed TWO perfectly good AC compressors by shutting the #$%^&* fans off when the car went into limp mode.

My question, which is really rhetorical as I can't imagine why it would be the case, is if there is any reason to not just run the fans nonstop when the ignition is on? Since the fan controller has been programmed to stop the fans in limp mode despite the AC compressor being on, it would seem that everyone should bypass this worthless component.