Hey guys,

I have a 2001 Audi tt 225 roadster which runs normal temp when driving(88-92) but when idling or sit and go traffic it will slowly rise to 99 or 100 degrees then both fans turn on and it goes down to 93 or so. The fans never run by themselves, or on slow speed. I also tried turning on the ac to see if that would trigger them, and neither fan turned on with the AC running.

What triggers the low speed fan to run, and at what temperature? Also shouldnt atleast 1 fan turn on when I turn on the AC?

Thanks for any help!

 

When the ac is on (Econ off)and idling, both fans should spin at low speed. If needed, the fan control module and thermo switch will toggle the high speed in.
With the ac off idling, the low speed should come on at 95c or so, high speed at 100c more or less.
The problem with VW fans is the low speed resistor on each fan burns out, leaving you with just high speed operation and a lot of current load during ramp up,
hence the melting of the fuse holder above the battery.
Loads of posts on numerous sites regarding this problem. A lot of links about installing external resistors to the fans, but they are old and some not available.
https://forums.vwvortex.com/showthread.php?3891609
The latest post on this link is 10 years old. Hard to believe the problem just went away, unless fans available for purchase have been upgraded and been made less
expensive.
The large fan on my '02 TT is dead, hence the searching. Smaller unit works but makes the ac cut out and higher than comfortable temperatures when idling in
traffic.
Sounds like both your resistors are toast, and the high speed is toggled at temp. This needs to be addressed before something toasts...
Anyone with input regarding the fans available now?