1 / 4   Air conditioning is indispensable for train travelers in summer. However, for China’s high-speed train, its maintenance is not easy. /VCG Photo

2 / 4   When a train achieves a certain mileage, the air-conditioning units will suck some sundries into the heat sinks, affecting the cooling effect. /VCG Photo

3 / 4   Cleaning staff from northwestern China’s Xi’an Railway Bureau have to wash more than 500 units manually each day at high temperatures, to ensure the normal functioning of the equipment. /VCG Photo

4 / 4   Workers in protective suits use high-pressure water guns and special long-handle brushes and they have to endure hot air generated by the power supply. /VCG Photo