2005 S4 aux fan not working w/ AC on

[gone postal]

I picked this up as a project car. I had to fix a bunch of leaks, but now that it's back together, this is my first chance to really run the car. I noticed the a/c isn't blowing cold. The main fan is working fine, but the aux fan isn't on. I bypassed the module and the fan works w/ steady 12V. I was getting approx 7V from the module (which was close to what I was seeing w/ main fan too). In VAGCOM I see the compressor is on and the load request was like 27% for main and 9% for aux, but the aux fan wasn't actually spinning (cool day out today which prob explains low load requests). Even on max a/c, it didn't increase a ton. I ran the output test in VAGCOM for aux fan and it was definitely working (I assume test ramps up to 100% b/c it was really spinning!). So that tells me everything electrically is good w/ the fan circuit, but still not sure why I'm not seeing it spin w/ a/c on. Is it possible that the fan is just "worn out" and the 7V that the module was sending it wasn't enough to spin it?

[gone postal]

Damnit. I just found the other thread. Sorry guys. Mods please delete

[Terry.Reese]

Damnit. I just found the other thread. Sorry guys. Mods please delete

What other thread, been looking for an answer to this as well.

[gone postal]

No replies to that thread either.

[jv_atc]

Hi, any progress? I have an identical issue, been searching for days...

[Velox]

Maybe this will help you in the right direction:



So your 9% duty cycle could be a problem


Also:



Your 7 voltage could be a problem,
They say if fan doesn't turn on at 9 volts replace fan.
if output doesn't reach 9 volts, check/clean wiring to/from control module or replace control module.

I would first try to figure out why you aren't seeing a minimum of 10% duty cycle and to see what happens if you can get it at 10% duty cycle before replacing anything.

[jv_atc]

I solved this issue in my 05 S4 cab. recently. It was the fcm on the rail as pictured above, and not the fcm in front of the radiator.