Hows everyone doing? I have a 04 Audi A4 quattro 1.8 im having a problem with the fans not coming on My over flow tank was busted and i just replaced it . i replaced the Temperature sensor on the lower radiator hose. i test the fan works fine. i tested the relays under the ECU on the firewall all good. i replaced the thermostat. I really dont know how to test the fan control unit. but i dont want to spend 250 bust to find out im wrong. if theirs a way to test it im all ears. one more thing there is a sensor on the thermostat housing and i have no clue whats its for

 

nevermind lol