Evtechnician

My son purchased his first Audi (2005 A8L) last year, and it now has 132,272 miles. It seemed to be well taken care of and has not given any problems until now. The problem is when traveling on the highway or sitting still in the car park with the AC on the temp will slowly rise until it gets too hot and he has to turn it off and let her cool down. If he drives it gently on surface streets it does not seem to overheat. We are in southern California and the weather has been 70 degrees pretty much all the time.
I looked at the fans when it was hot and only one was spinning . I wanted to check the 40 A fuses but I can not find their location for this model . Would anyone point me to the correct location for theses fuses ? I read on the latter cars they are behind the fog light on the passenger side .
Thanks

dvs_dave

The fans don’t have specific fuses. The fans are controlled by the fan control modules which are built into the fan motor assemblies. You will need VCDS to properly scan, test and diagnose. Or just take your chances and swap out the seemingly bad fan module. Not much space in there do it so a fiddly job unless you put the front end of the car into what’s called “service position” to give you the clearance needed.

MP4.2+6.0

Turn off HVAC completely and then see if the one fan still spins, or it cuts out too. If so, you have essentially no temperature related fan function. With AC on ,if that fan is on from cold start, same answer--you have no engine temp related fan function ,just the A/C related operation. Doesn't solve it, but at least can help in diagnostics

Thermostat is also possible.

Like in other reply, really need a quality scan to assess further.