2007 auxiliary cooling fan not working

If the fans worked prior to the ECU being repaired then it's not the fans it's the ECU. Bring it back to the dealership and have them explain what they did to repair the ECU. If they replaced the ECU then something must be wrong with the new one (assuming it is new - probably not but refurbished). Don't roll over and play dead. Dealers like passive people who just take what they say. You have to be firm in saying that there was nothing wrong with the fans till they did the repairs and they need to fix it for FREE!! Good luck.

Thanks for the input. The dealer only fixed a broken wire that powered the ECU. Actually the repair was only splicing the wire. However, the fans worked fine prior to the repair. Are they responsible for causing the fans not to work?

That's pretty expensive labor you paid just to splice a wire. Most shops will not take the time to investigate what is wrong with a part other than recommend replacing it. It's just unusual timing that the fans are not working properly after your car was just serviced. Nonetheless, don't drive your car that way as you will create more expensive problems like damage to your engine due to overheating. If you don't trust the shop, try another one and get another opinion or at least negotiate a discounted labor rate to fix the new problem.

Note that the ECU or ECM controls the fan turning on and off and the rate of speed. If the ECU/ECM was worked on by the last shop it is possible they created the new problem if in fact you know the fans were both working just before you brought it in for the ECU repairs. Bring it to another VW dealership and get another opinion if you have no faith in the last dealership. Good luck!