Cooling fan running for no reason.

[Moffat]

Over the past few days, I've noticed my cooling fan running quite often. It isn't when the car is up to temp, and can even be from cold. It's warm weather at the minute obviously, but i don't think that's to blame. Also, i've been leaving my aircon off and listening for it, and it still comes on. Is this the sign of a sensor staring to fail, and kicking the fan in unnecessarily?

 

[NHN]

Fans will run with aircon on & hot weather

 

[bizza25]

mine stared coming on randomly even when car was switched off. kept running the battery down until i caught it on one night!
turned out to be the heater plug fuse under the ecu had partly melted and sort of fused itself onto the board. i pulled this out and replaced and all ok since. might be worth a look around the area of the fan for any cracked or shorted wires, and up to ecu if a diesel.

 

[Legend7]

This happened to my old car, it turned out to be one of the sensors. Apparently I was told there are 3 sensors which affect the fan

 

[phil76]

Sometimes its the fans themselves which knacker up and cause this problem too so they are running constant

 

[Moffat]

Fans will run with aircon on & hot weather

Yes, I know why and when a fan will run, but it's running outside of normal situations.

It can be from cold, without the aircon, blowers, or anything turned on.
It's an S3 if it helps any.