"Ton AC" refers to the cooling capacity of an air conditioning system. In this context, "ton" is a unit of measurement that represents the amount of heat an air conditioner can remove from a space in one hour. It does not refer to the weight of the air conditioner itself.
One ton of cooling capacity is equal to the amount of heat required to melt one ton (2,000 pounds or 907 kilograms) of ice in a 24-hour period. It is approximately equivalent to 12,000 British thermal units (BTUs) per hour. Therefore, when you see an air conditioning unit described as "1 ton," it means that it has a cooling capacity of 12,000 BTUs per hour.
It's worth noting that the term "ton AC" is commonly used in the United States and some other countries. In other regions, such as Europe and many Asian countries, the cooling capacity of air conditioners is often specified in kilowatts (kW) instead.