A heat pump type air conditioning system (A) for an automotive vehicle. The heat type air conditioning system (A) comprises a first unit (10) including a heater core (11) through which an engine coolant of an engine flows, and a first heat exchanger (12) which forms part of a refrigeration cycle including a compressor (1) and a first condenser (3), in which a refrigerant circulates in the refrigeration cycle. A second unit (20) is provided including a second condenser (21) and a second heat exchanger (22) which are fluidly connected in parallel with the first heat exchanger (12). A valve (V2) is fluidly connected in series with the second condenser (21) and disposed such that a part of the refrigerant is introduced through the valve into the second condenser (21) and the second heat exchanger (22). A sub-heat exchanger (30) is disposed outside the first and second units and fluidly connected in series with the second heat exchanger (22), in which the refrigerant flowing from the second heat exchanger (22) is introduced into the sub-heat exchanger to be heated by a part of the engine coolant, the refrigerant discharged from the sub-heat exchanger being returned to the compressor. An electromagnetic clutch (40) is provided such that the compressor (1) is drivably connectable with the engine therethrough. The electromagnetic clutch is engaged to establish a driving connection between the compressor so as to operate the compressor and disengaged to cut the driving connection so as to make the compressor inoperative. A control device (C) is operatively connected to the electromagnetic clutch (40) for controlling the electromagnetic clutch to be disengageable in accordance with a temperature within the air conditioning system (A).