A method is provided for operating a laundry dryer having a rotatable drum for accommodating clothes to be dried and an apparatus for circulating drying air through the drum. The method comprises the steps of performing a drying cycle selected by a user, wherein the drying cycle comprises predetermined drum movements over time depending on the cycle selected, detecting values indicative of the temperature of the drying air exiting the drum, based on said detected values, determining that the clothes inside the drum are in tangling conditions and starting an untangling operation for untying the clothes inside the drum. The untangling operation comprises modification of the predetermined drum movements. The modification comprises at least one of the following: stopping the rotation of the drum, reversing the rotation of the drum, modifying the speed of rotation of the drum, at the end of the untangling operation, either resuming the predetermined drum movements associated to the drying cycle that was running before starting the untangling operation, or performing drum movements over time different from the predetermined drum movements associated to the drying cycle that was running before starting the untangling operation.