Test radiator fans

Hello to each other, on a highway ride in the current heat, the on-board computer has repeatedly pointed out to me that the engine is too hot and I should stop. With an immediate reduction of the speed I managed to quickly lower the temperature again. I guess the fan refused its service. The hoses to the cooler and the heating were all four always hot, dre cooling water tank is normally filled. How can I test the fan operation? Where can I find the fuse, the relay and the temperature switch? Maybe someone has a quick tip. Today it was only 25° outside temperature and the ride went again without any problems.