Air conditioning system for vehicles

An air conditioning system for vehicles comprising a refrigeration cycle having at least a variable displacement compressor, a condenser and an evaporator, and a displacement controlling means for outputting a displacement control signal to the compressor, characterized in that the system has a torque calculating means comprising at least two torque estimating means of a saturated area torque estimating means employed in a case where the compressor is driven at a maximum discharge amount and a displacement control area torque estimating means employed in a case where the compressor is driven at a discharge amount except the maximum discharge amount. It becomes possible to accurately estimate a compressor torque over all areas including the saturated area and the displacement control area.