2004 A6 radiator fan keeps running

I have a 2004 Audi A6 2.7t with about 35k miles. Radiator fan is running for 10 - 20 minutes even when the engine is not hot, for example, after a 1
or 2 mile drive. Dealer did not show any diagnostic faults and recommended replacing the temperature sensor, Had the local shop replace the sensor (dealer wanted over $300) but the situation remains.
So the questions are:
1. Is this normal behavior that I just don't notice before? 2. Any other ideas for what to check or replace?
Thanks for the help.
Steve
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Steve-public wrote:

The thermo sensor would have been my guess. If you are sure that the new one is good I would suggest sticking relays. If the speed of the fan is the slowest speed it might be related to the AC that causes the fan to run in the slow speed when the compressor is operating.
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I think the new sensor is fine. The behavior is identical now as before the changed sensor. I noticed today that if I start the car for only 30 seconds and then shut it off, the fan still comes on for 10 minutes and then turns off. I was also assuming it was the relay but the repeatability of the problem and the timing for the eventual shutoff is making me wonder. I have a call into the mechanic to see what other ideas he has. Any other thoughts are greatly appreciated...

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If it's like my 1999 A6 then the fan runs all the time when the a/c is working. Makes a hell of a noize.
M.
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