An air-conditioning system for a vehicle includes an electronic control unit which detects a collision of the vehicle and activates an air bag of the vehicle, and a circulation passage for a refrigerant or R152a. The system further includes a discharge device which discharges the refrigerant from the circulation passage in the engine room when the control unit outputs an air-bag activation signal. The discharge device includes an electromagnetic valve adapted to opened to discharge a refrigerant from the circulation passage in the engine room when the control unit outputs the signal.