Machine comprising a treating chamber for drying humid articles by process air, a process air guide for guiding the process air through said treating chamber in a first circuit closed in itself, said process air guide comprising a first blower for driving the process air, a heat source for heating the process air and placed upstream of said treating chamber, and a heat sink for cooling the process air and placed downstream of said treating chamber, wherein said heat source and said heat sink are included in a heat pump (7, 8, 9, 10, 11) wherein said heat source is provided for transferring heat from a refrigerant to the process air by liquefying the refrigerant, and wherein said heat sink is provided for transferring heat from the process air to the refrigerant by evaporating the refrigerant, said heat pump (7, 8, 9, 10, 11) further comprising a controllable compressor for compressing and driving the refrigerant through said heat pump (7, 8, 9, 10, 11) for transferring heat from said heat sink to said heat source, an expander for expanding the refrigerant, and a refrigerant guide for guiding the refrigerant through said heat pump (7, 8, 9, 10, 11) in a second circuit closed in itself, and an operating unit for operating said process air guide and said heat pump (7, 8, 9, 10, 11) in treating the articles, said operating unit including a power sensor for measuring a power input to operate said compressor, and a temperature sensor (14, 14') for measuring a temperature of said refrigerant in a continuous part of said refrigerant guide including said heat source and excluding said compressor and said expander, wherein said operating unit is provided to operate said compressor to perform at least one drying process for drying the humid articles placed in said treating chamber, said drying process including the following steps: (a) initiating operation of said blower to drive the process air through said process air guide, initiating operation of said compressor to increase compressing and driving said refrigerant through said refrigerant guide, for a respective predetermined time interval; (b) measuring the power input, and measuring the temperature, and operating said compressor at a power input equal to a respective predetermined power input until the temperature has reached a respective predetermined temperature threshold, and from then operating said compressor at a power input below said respective predetermined power input to keep the temperature at said respective predetermined temperature threshold, and continuing step (b) until the drying of said articles is completed. (a) initiating operation of said blower to drive the process air through said process air guide, initiating operation of said compressor to increase compressing and driving said refrigerant through said refrigerant guide, for a respective predetermined time interval; (b) measuring the power input, and measuring the temperature, and operating said compressor at a power input equal to a respective predetermined power input until the temperature has reached a respective predetermined temperature threshold, and from then operating said compressor at a power input below said respective predetermined power input to keep the temperature at said respective predetermined temperature threshold, and continuing step (b) until the drying of said articles is completed.