A portable air conditioning unit for ventilating a room having walls , a floor and a ceiling, and being capable of housing a patient's bed, comprising at least one air supply unit and one air exhaust unit, where said air inlet unit comprises a guiding slot diffuser for guiding an airstream in a certain direction, such that a patient, lying down in said bed on his back, receives said airstream frontally, and that said exhaust unit is arranged near the floor and near a head end of the bed such that air is arranged to enter the portable air conditioning unit after having ventilated the patient. The air supply unit is also provided with means such that fresh air can be forced through the diffuser forming a first airstream and that said first airstream leaves the diffuser bringing with it a larger mass of fresh air leaving the portable air supply unit via perforated sheets, forming the airstream devised to cool the patient.
