A4 B7 Fans running with car off
 

Hi,

So I've been having ongoing problems with my fans running without even starting the car. Basically I go to the car, open the door, close the door, after about 10 seconds the fans kick on full speed and don't stop until I open and close the door again. All this happens without me doing anything with the key. Even happens when I disarm/arm the car before and after.

FYI, i've replaced Fans, Fan Control Module, Relay, Coolant Temp Sensor (the one behind the engine), I've recently done the timing belt, pump, tstat, but the problem existed before this too

Any ideas on whats kicking the fans on?

2.0 Auto Quattro btw.

The temp sensor that controls the fans is located in back of one side of the radiator. One if the symptoms of them going bad is the fans staying on all the time. This can run the battery down also.

I can't find such a sensor? the only one i found is the one at the back of the engine:

https://genuineaudiparts.com/parts/2...iagram=1398080

number 24 in the link

Interesting. Most of the ones I've worked on have a separate sensor for the fans in the radiator. My 03 A8L has one just like the ones in my 944's... Let me do some digging.

ok thanks Dave. Let me know if you come up with anything

I'm not coming up with anything other than there is just that one temp sensor, the one you've replaced. Typically, there usually is a dedicated temp sensor for the fans in the radiator but apparently Audi doesn't have this type of setup on your particular model.

I'd check for wiring harness damage on the fan assembly up front. Maybe something is shorting out.

ok, I've checked wiring near ECU and Relays and found nothing out of the ordinary. I think wiring from the control module is fine because the fans function fine other than this particular issue so I know the fans are getting powered, the control module is getting signals and power and the relays are firing on.

I need to traced the wiring under the dash from the Relays to the fuse box and back to the fan control module. Perhaps its something there....