Ndbert

I recently bought a 2005 a4 with the 1.8t. After about a month the car started to overheat and the ac would blow hot. Changed the rear coolant flange as I found it leaking. Replaced the coolant temp sensor and the 219 relay. Also replaced fan control module and the fan still will not engage. I can apply 12v directly to fan and it runs fine. i attempted to jumper out the radiator thermal switch to get it to engage but it will not run under battery power and I am hesitant to jumper it out with the car running. Anyone have any ideas or possibly know a fix.