Audi a3 2.0 ltr tdi radiator fans not working

[gary keyworth]

Hi just wondering if anyone can shed a little light on a problem I have with audi a3 tdi both fans are not working , it has had a little bump on the front end and I have had to replace the 3 rads and fans but car starts first time and runs great but at 90 temperature they do not kick in , now ive had a look at all the fuses in car and under bonnet, swapped the main fan for another as it has a regulator in it im told , I expected it to work but no luck , just wondered if there was any help out there, any help would be appreciated

[CrutyRammers]

Not familiar with your Audis, but a radiator circuit is likely to be sensor - ecu - relay - fused supply to fan.
So if the fans work (connect directly to a battery to check, but it'd be unlikely if they were all broken), the fuse is right, it's either the relay, the temp sensor, or a wiring fault (broken earth sounds like a good bet if all 3 are not working).
I'd imagine such a specific fault with the ecu would be unlikely so I'd check the rest first.

Note - might be different than above if it's all canbus, but there will be a supply to the fan somewhere, then a connection from fan to earth.

[AJB]

Are you sure the fan should have kicked in? 90 degrees is normal operating temperature for most engines these days, so I wouldn't expect the fan to be running just because the engine has reached 90. Once the thermostat is fully open and the temperature is still rising above 90 then the fan should run.

[andyiley]

Find the temperature switch that starts the fan & short out the wiring to see if the fan starts, if it does you need a new switch, if it does not you need to check fuses & the fan itself by hot-wiring it to see where to go next.

[Polome]

If your car has AC switching on will start fan (or fans)...this would be easy check on fans working. Switching on at correct temp is another matter .

[packman10_4]

On earlier Audis and VW's the left fan looking in the engine bay was the aircon fan now i think both are the aircon fans. You need to get it p[lugged in to see whats going on. Ive just done a S5 Audi the fan was on all the time these have a problem with the motor controllers melting as there mounted on the rear of the fan housings ...

[gary keyworth]

Thanks for your time reply to my problem with the audi a3, I have only just seen the replies ! !, the car is still on drive and iam still well stuck , but I will take all comments on board to test it, to tell you the truth I did wonder if engine would be hot enough at 90 for them to kick in, the a/c rad is empty as I have replaced all 3 rads and no front bumper on, but I did have car plugged in and it came up radiator fans connection fault, is there a relay fuse, I know there is a regulator built into the larger fan but I have replaced it, and still no joy

[gary keyworth]

I am told that there is canbus system on my car I have two lights on dash ,the yellow steering wheel and the esp light , I was told that these are on because the head lights/fog lights are not connected and therefore not completing a circuit, would the canbus system also stop the fans from working