another radiator fan issue
 

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.

Seems like you did everything you can to check the fan. The relay would of been the first thing I would of checked. Just out of curiosity, what color is the coolant thats in the car right now?

Coolant is pink. When I changed the coolant flange I flushed the system and put in new G12. When I check voltage going to the thermal switch across the pin I am 4.66 volts no matter if the ignition is turned or not.

car will not start
 

I was having the same issues with my car. My husband replaced the CTS and now car will not start at all. He says it's not getting fuel. When it was running, it would crank a few times before starting, run hot in the city. Air conditioning would blow hot at stop lights. The coolant light would come on and sometimes an oil pressure low light would come on. Now that he's replaced the CTS, it won't start at all. Has anyone else had these problems?

Changed out the radiator thermal switch today and still no fans. I am starting to think it is a wiring issue somewhere. Does anyone have a link to a good wiring diagram or a list of what my readings should be across the pins? I have searched and can't find a breakdown of what relays and fuses are in this system besides the 5a alongside dash and the 219 relay.

Fromaka I have had similar starting issues and continue to have them even after replacing everything in the system it feels like. Not sure how they coincide as this is my first experience with an Audi. I am about to go back to driving my old Jeep.

I have checked the wiring to the thermal switch connector and get 4.66 volts. Jump the pins does not make the fans run. I hardwired driver side fan and it spins with ease. I get no movement from the passenger side fan now. Could the passenger side fan motor being inop cause both fans not to run? When I finally get this figured out I am writing all the steps I went through down to try and help others first. This is worse than working on a Boeing product.