Audi Repair: Air intake Fan?, engine cold, thermal switch

Question
QUESTION: I have a 98 A4 2.8L quattro. There is a fan to the left of my engine (while facing the car) that is coming on while my car is off. Any idea what could be happening?

ANSWER: Sounds like the thermal switch is malfunctioning, or is the engine really hot?  The fan is supposed to be live at all times, so if the engine is very hot the fan will stay on, even with the ignition off, keys removed and doors locked.   Let me know,  Jan

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QUESTION: It was happening 2-3 hours after the car had been turned off. Is the repair most likely only going to entail replacement of an electronic switch? Is it something I could do myself?

Answer
Yep the switch is usually in the radiator, so you will need to do this with the engine cold, and you'll probably loose some fluid, the amount depends on how fast you are...!  You can cehck the switch by pulling one of the terminals while the fan is going, it should stop.  Then check the resistance in the switch with a Ohmmeter.  If the engine is cool, it should be open circuit.  Let me know,  Jan