Radiator fan has me pulling my hair out.

[speedytalon]

A Friend of mine has a 90 Tsi Awd like mine... and the other day a hose from his manual boost controller that was not zipped down made its way into the radiator fan (probly before it kicked on). When it hit what ever temp it comes on at it broke the fan blades off. It sheared off where the bold that holds it in is at. He went to the scrapper yard and found one for 27 bucks. We installed it and when the car heats up it does not kick on. I opened the ol' trusty Chilton and read up on testing the fan motor. We hooked it up to the 12v battery and the fan came on with no problems. We put a new fuse in and still nothing. The only thing I can think of is to test the wire harness with an ohm meter to see if maybe a wire fried. Can anyone think of what else could be causing it not to kick on? We made sure the temp sensor plug was on good.

I’m stumped

 

[speedytalon]

bah, i put this in the newbie area instead of the tech area...

 

[xveganxcowboyx]

You put it in both.

Making sure it all the wiring is solid would be a good idea.

 

[MadTripper]

There must be a temp sensor in the radiator that sends the signal to turn your fan on (someone with a bit more experience can clarify if I'm off here). Additionally, you could bring the car up to temperature and see if you are getting any voltage on your fan plug. Trace back from there and you should be able to find the issue. I had a cherokee with a faulty temp sensor a while back. I think it was 19.00 from napa for a replacement.

Worse case, you could build a small circuit using a thermistor and a potentiometor to turn the fan on at whatever temp you wanted. A bit on the extreme side but still a cheap option.