2013 S5 3.0 coolant fans wont activate

[czellars]

Hello All,

I have a 2013 Audi S5 3.0. Car was in an accident that smashed the front end. I bought the car after that and am trying to repair. I have new: radiator, radiator fans, waterpump, thermostat, temp sensor, ac condensor, heat exchanger, hoses, pipes, pulleys are all new. VCDS shows temp hitting 100 celsius but the fans wont activate. I can trigger them from VCDS but they never turn without VCDS. Even when I first start the car they don't activate. Nor do they activate with AC on. VCDS shows Fan control relay: fan run-on = 0 / Radiator fan 1: run-on status =2 / radiator fan 1: activation = 10.156250 % (same for fan 2). I havent found any blown fuses and believe that the relays live on the fan motors. Any advice or help would be great.

[czellars]

Today I let the car run until it got up to 100°C and the fans did kick in! Research shows that the car has to get up to around 105°C for the fans to even start. Also before that I replaced the AC Pressure sensor that sits on the AC condenser because VCDS output error 00256 - A/C Pressure/Temperature Sensor (G395) 008 - Implausible Signal. I read that may play a role with fan functionality. Either way the sensor and wiring were suspect. For anyone that follows then I believe that the AC pressure switch may have solved the problem!

[Smac770]

If the G395 is not working, the A/C system is disabled. Thus turning it on would result in nothing, no command by the J255 to the J623 to spin up the fans.