The invention relates a method for controlling a laundry drying machine (1; 201) equipped with a heat pump system (50) during a drying cycle. The laundry drying machine (1; 201) comprises: a control unit (UC1); a rotatable treating chamber (9) where laundry can be introduced to be dried with a drying air stream; a heat pump system (50) including a compressor (52); a passive switching device (70), not controllable by the control unit (UC1), adapted to cut the power supplied to the compressor (52); an active switching device (72), controllable by the control unit (UC1), for selectively switching on and off the compressor (52). The method comprises the steps of: starting a drying cycle; activating the heat pump system (50) by switching on the compressor (52); rotating the treating chamber (9); evaluating if an inversion of direction of rotation of the treating chamber (9) has to be performed and, if an inversion of direction of rotation has to be performed, evaluating if an operating condition of the compressor (52) which can cause the activation of the passive switching device (70) exists; if the operating condition does not exist, then performing the inversion of direction of rotation of the treating chamber (9), otherwise if the operating condition exists then performing the following steps: switching off the compressor (52); performing the inversion of direction of rotation of the treating chamber (9); switching on the compressor (52).