I already found the mistake in my vw. A few weeks ago i replaced a tube from the radiator circuit. In that operation i replaced and cleaned the radiator... and i made i mistake, i didnt "bleed" the radiator well, so it gained air... and air prevents the coolant to get into touch with the termostat, so the 1st fan velocity didnt worked... i looked in the net and come with a solution, i already did it and now its working well.
1 - warm the car to the middle temperature without the cap that covers the coolant resovoir.
2 - And now the trick... turn on the heat on the car to maximum... the coolant will run through the tubes to warm the air to warm the veihucle interior, and you will see bubles in the resovoir... after a few minutes until it stops give some gas to the car... just a little to bring the air up. turn off the car.
3 - with a key, unscrew the termostat until it comes a little water, as soon you see water, screw it again. cover with the cap the resovoir and try it out.
For me did work, try to find in google.com HOW TO CLEAN CAR RADIATOR
I just hope i dont have a leek in somewhere else, because if i have the air will enter again and bring back the problem. tomorrow i will try it again to see if it is ok.
Try this and give me your result to
ricardo.oliveira@sm.efacec.pt
Hasta la bista................