thanks for the reply. I checked electrical system with two electricians. They said that no fault. I'm really fed up with this now. If AC works it works the whole day, even if I stop/restart the car.
My car is toyota vitz 2008. Ac works perfectly well. But sometimes it doesn't switch on not even the AC bulb. I change the ac switch also. Did a vehicle scan and it shows no fault. Does anyone know a reason or place to check?