Radiator belt fan replacement

nickid · #1 27th December 2013, 04:50 PM

I found a piece on google about changing the belt fan with an electric one but can find a DIY. Can someone help?

nickid · #2 28th December 2013, 08:42 PM

Can I link it to the other fan ? also what temp does the other come on? will I need to change the thermo switch?

notorious · #3 28th December 2013, 09:41 PM

Here is how radiator niche looks like when radiator is removed.

Notice that effective radiator aria is divided vertically between visco fan (left) and electric fan (right). Vertical divider is made of special foam/rubber to separate zones and has an irregular shape. The 'zones of influence' of electrical fan and visco fan are carefully balanced. There are also two pairs of flaps in lower right area under electric fan. Flaps will open by the incoming airflow when car is moving and will play their own role in complex equation of optimal cooling. In the right lower corner there's a small blank off area to reduce radiator surface for my specific engine by restricting air flow through it.

Switch is also complicated. It has two separate switches inside, activating at different temperatures. One to activate first speed of the electrical fan and other to activate second speed. Switch is directly responsible for critical task of switching the fan at the right speed at the right time. Switch on my car is manufactured in Luxembourg. Audi doesn't buy them from China. Different engines were supplied with different switches activating at different temperature thresholds and all fans are different too.

In front of radiator we also have aircon condender and operation of the whole ecosystem needs to be balanced with aircon depending on if it is "on" or "off". Visco fan is also fine balanced system and is just another variable in complex equation...

This is scientifically engineered stuff. People spent time calculating, modelling, testing and certifying all this to work together, making sure engine and aircon are running in optimal temperature mode in all conditions for each specific engine. And running reliably, as it is easy to lose the engine if we overheat it or systematically underheat it.

Now what problem are you trying to solve? Why on Earth you want to replace visco fan with electric fan? You have nothing else to fix in the car?

nickid · #4 28th December 2013, 10:21 PM

I have read that the engine runs better without having the original fan on all the time, and having the electric fan, I Will have less noise and only have it coming on at a certain tempture.
I have bought a 16 electic fan off eBay and was wondering if i can attach it to the other fan? And if so how

ainarssems · #5 29th December 2013, 12:01 AM

You do not really want it to come on together with the other fan. Stock electric fan comes on when AC needs it or when coolant temp exceeds threshold(115C if I am not wrong and 120C for speed 2). If you did it fully electrical you would want it to come on around 98C. And on the other hand you can have engine still cold but AC calling for fan on so you could have engine t 50C and 2 fans running.

Original setup will run just fine if viscous coupling is OK. It might rob you 0.5HP but you are not going to feel it. In worse case scenario if viscous coupling is stuck permanently on you might loose 4HP at 7000rpm but you will still not feel loss of power, just noise from fan.

If you relly must have second electrical fan you will need separate sensors/logic for it.