Air conditioners are always rated in Ton's capacity instead of kW because Air conditioners are designed on the basis of the quantity of heat removal from a room, hall, or specific area. Quantity of heat is termed in Tons means if an air conditioner is able to remove 1000 kilocalories of heat or 4120 kilojoules or 12000 BTU of heat in an hour that AC is rated as 1 Ton of AC because of 1000 Kilocalories or 4120 kilojoules or 12000 BTU equal to one Ton of heat. Also, this is the same case for freezers and refrigerators i.e., refrigeration systems.
Good to know:
BTU = British thermal unit. A measurement of heat, specifically, the amount of heat needed to raise the temperature of a pound of water by 1°F.
1 Ton = 3,516.8528 Watts = 3.516 kW.
1 Ton = 4.714 Hp