Warning symbol Cooling water in AC flashes constantly

Moin Forum,

Need your help. The V8 permanently lights up the warning symbol for cooling water in the Auto Check System. Even if you start the car in the cold in the morning, it will alert after about 20 seconds.

It only occurs as soon as the engine runs, when only ignition is on it remains extinguished and no matter how warm it is. All temperature sensors and cooling water balancers are new. But it won't go out. Can it lie on the instrument cluster or is there another possibility ?

Thank you and greet