Both Radiator fans keep running after engine turned off

I've searched several threads for my specific issue, some seem close......but?

2000 Golf automatic, 191,000 miles on it. For awhile now when I turn off egine, the radiator fans continue to run for 5 plus minutes. It's not temperature related because even if the car is stone cold and only runs for a minute of two, the fans still continue to run. It hasn't been a problem yet with running down the battery, but still I'd like to address it.

Recently during our state yearly inspection process, my mechanic stated that the bottom of my radiator was moist and the I start the process of planning for a new radiator. Several threads I've read talk about a sensor ( temp fan?) located on the lower radiator and also a fan control unit being bad.

Any ideas of the most common culprits.

I would also say the sensor. That sensor has live power to it even with the car shut off. When it reaches a certain temp the switch opens up to turn the fan on and when the temp drops enough the switch closes back down. That is how it is on my older rabbit and I assume the switch works about the same. You can always test it in water and reach to a boil and then cool down again with a circuit tester to see when it opens and closes. Get the oring or sealing washer that goes on it and maybe buy a switch ahead of time. Do it on a cold engine so you only loose the coolant in the radiator only. Have a little extra coolant around and pull that switch out. Again I don't know the exact location other then my rabbit as my Golf hasn't had that problem. Check your bentley manual for the how to on it. It you don't own one then I would get one.

Fuse #16 on the panel in the dash is burned out.