I am very involved with sound quality car audio competition from a judging and competing aspect. I have spent alot of time and money on my system and am going through the tuning stage to get it sounding just right.

One of the first things I noticed with the 6, was that the internal blower fan runs all the time when the key is in the acc and/or car on position. This is the same for most Pugs I have found, and in fact, it's common for most european cars (my mother's Alfa was the same too).

The fan noise is intrusive (because my stereo is not always about doof doof - much of my music is quiter acoustic, etc), distracting, and also aids in draining even a deep cycle battery just a bit quicker than it should.
Here in Australia, there is no need to have the fan running all the time.
So, I set about trying to find a way for its use to be more limited.
Searching on this and other forums around the world proved absolutely useless I must say. Oh well, perhaps I just had to figure it out myself.

In the end it actually wasn't that hard really. A basic knowledge of relays is required because we'll be using only one new piece of jumper wire to the A/C systems existing relay.

In deciding how to do this, I had to take into account that the mosfets that help govern the blower motor speed do get warm/hot. The fan speed controler is on the A/C circuit and is always on when the key is in the ACC position. That's why the fan runs even when the speed is set to zero by the user at the heater controls on the dash - to keep these two mosfets cool. Others who hav simply put in a switch on the main 12v high current wire to the blower risk burning out their new switch and also burninig out the motor mosfets. The mosfets are always on when the controler/brain is on.
Any switching needs to be in the system before even the controler brain in the centre console so that the brain is of as well and not just the blower motor. Doing it this way means you only need a piece of wire and you don't have to buy any additional hardware/switches, etc and then find a home or them somewhere.

Anyway, here's how it's all done.

As with any electrical work done on any car, always disconnect the -ve at the battery first.



You're then going to undo 3 screws for the steering wheel shroud here



and one for access to the fuse/relay housing here



You need to remove this relay



You'll also need to gently lever off the headlight level control and instrument dimmer control panel that's to the right of the steering wheel, above the fuse box panel that you have just removed.

This will give you access to the green A/C circuit relay indicated above.





Now, you need to find the 'On' wire in the group of wires that come out of the ignition barrel.
I did this with a simple 12v probe and process of elimination.

The battery was connected up again and the key switched to on.



The thick orange wire was the wire I needed.
When the key was switched to acc, my probe light went out.



Why did I need this?
Well, I needed a 12v 'on position' only wire to act as the new 12v trigger for the relay that switches on the A/C blower, etc.
I also needed to find the current 12v trigger in for the relay. Looking at the relay gave some clues because of the diagram on its side but I also used the probe again to find the 12v wire just to make sure.





The wire needed is blue/brown. The trigger earth is the yellow/green.

We need to basically move the 12v relay trigger from the acc circuit to the car on circuit. Easy really.

So, disconnect the battery again and cut the current 12v trigger wire, making sure you leave enough sticking out of the relay because you'll need something to solder to in a minute.



The end of the old 12v trigger wire is knotted and insulated with heat shrink.



The new jumper wire is soldered to the end and insulated.



The other end is soldered to the on position wiring and insulated like this.



I reconneted the battery, switched the car to acc and left it for a while.
I then checked that the blower mosfets were not running and heating up. They're under the metal heatsink in the blower assembly accessed from under the glove box.



The result - STONE COLD!
Perfect.

So, now it only comes on when the car is on and not when I'm listening quietly (or loudly) to this...



Disclaimer: I did this and knew I could stuff things up and it would be my own fault. I'm not twisting your arm to do it, so if you do decide to do this too and and stuff something up, that is your fault.

Have fun

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'99 306Gti