Fiat Punto 176 1.2 60hp, engine gets hot, heating stays cold

Hello dear Fiat municipality! My girlfriend’s car has been having problems for 1 week. As I said, after a short driving time the engine gets warm quickly. After about 15km I stopped because the temperature indicator had almost reached the red area and touched the cooling hoses. The upper hose to the cooler was hot, the lower one was only lukewarm to cold. From the ventilation comes ONLY ice-cold air! I have read a lot like thermostat, thermoswitch, water pump, ZKD. Since my girlfriend the car t I wanted to ask if someone had the same symptoms and what was the cause. Then I could fix the car on Saturday. Greetings Jubi