A few days ago my TT started overheating in stop and go traffic and the AC stopped blowing cold air. I noticed that neither the AUX fan nor the AC fan are turning on so I automatically assumed that I have a bad fan control module. I ordered an OEM replacement and installed it today, but the problem still persists. I also checked the fuses on top of the battery and they are all good.

I found an old thread regarding a similar problem and somebody had mentioned to pull the number 16 fuse (10A) and then put it back. I did that and as soon as I re-installed the fuse both fans started spinning, but only for a few seconds.

I scanned the car for codes, but there are none for the HVAC or the cooling system.

What else can I try?

 

I found an old article that shows how to bypass the thermo switch on the radiator. I removed the connector and jumped pins 1 & 2 which should turn on both fans at low speed, but in my case that did not work. Next I jumped pins 2 & 3 which should turn both fans on high and that worked.

I repeated the test with the old fan controll module and the new control module - same thing.

So what can cause both fans to run on high speed only?