Originally Posted by lakejumper
Offroad- I purchased the exact same fans and when I bench tested them to get the correct wires, the fan would only "flinch" but wouldn't rotate. I used a 12v battery and tried every combination of wires. Am I missing something or do I have defective fans?
I would bet the fans are fine, you'd think that with only three wires it would be easy to figure out which is 12V+, 12V- and the rpm signal wire (you won't use this) but it's not.
It won't run backwards if you have 12V+ and 12V- reversed, keep trying and you'll get it.
When I got the right combination, I cut the rpm wire short and put a knot in the 12V+ wire to mark it. Since these are premade for computers with a motherboard connector on it, none of the wires are marked.
You also need to install the fans blowing up (the direction of the rising hot air), there should be an arrow on the body of the fan indication the direction of airflow.
On our TT I believe the wires to the original fans were the same color, but a quick test with a multi-meter will tell you which is 12V+. If you don't have a meter to confirm once you have the right wires on the fan, there are only two combinations on the TT wiring and only one will work.