Method for managing a thermal management device for a motor vehicle comprising a coolant circuit, in which a coolant is intended to circulate, said coolant circuit comprising: - a main loop comprising, in the direction of circulation of the coolant, a compressor, a condenser configured to exchange heat energy with a first element, a first expansion device and a first evaporator configured to exchange heat energy with a second element; - a bypass branch arranged parallel to the first expansion device and the first evaporator, said bypass branch comprising a second expansion device and a second evaporator arranged downstream of the second expansion device and configured to exchange heat energy with a third element, when at least the first evaporator is used so that the temperature of the second element at the outlet of the first evaporator reaches a setpoint temperature (T11-sp), a request to use the second evaporator is issued so that the third element reaches a first setpoint temperature (T15-sp1), so that the cooling power required for the simultaneous operation of the first and second evaporators is greater than the maximum cooling capacity of the thermal management device, and so that the thermal management device receives a request for cooling priority via the first evaporator, the management method comprises the following steps: - increasing the speed of rotation of the compressor to its maximum speed; - determining a modified setpoint temperature (T15-sp3) of the third element that is greater than the first setpoint temperature (T15-sp1) so that the temperature of the second element at the outlet of the first evaporator tends toward its setpoint temperature (T11-sp); - adjusting the opening diameter of the second expansion device so that the temperature of the third element at the outlet of the second evaporator reaches a modified setpoint temperature (T15-sp3), until the temperature of the second element at the outlet of the first evaporator reaches the setpoint temperature (T11-sp). - a main loop comprising, in the direction of circulation of the coolant, a compressor, a condenser configured to exchange heat energy with a first element, a first expansion device and a first evaporator configured to exchange heat energy with a second element; - a bypass branch arranged parallel to the first expansion device and the first evaporator, said bypass branch comprising a second expansion device and a second evaporator arranged downstream of the second expansion device and configured to exchange heat energy with a third element, when at least the first evaporator is used so that the temperature of the second element at the outlet of the first evaporator reaches a setpoint temperature (T11-sp), a request to use the second evaporator is issued so that the third element reaches a first setpoint temperature (T15-sp1), so that the cooling power required for the simultaneous operation of the first and second evaporators is greater than the maximum cooling capacity of the thermal management device, and so that the thermal management device receives a request for cooling priority via the first evaporator, the management method comprises the following steps: - increasing the speed of rotation of the compressor to its maximum speed; - determining a modified setpoint temperature (T15-sp3) of the third element that is greater than the first setpoint temperature (T15-sp1) so that the temperature of the second element at the outlet of the first evaporator tends toward its setpoint temperature (T11-sp); - adjusting the opening diameter of the second expansion device so that the temperature of the third element at the outlet of the second evaporator reaches a modified setpoint temperature (T15-sp3), until the temperature of the second element at the outlet of the first evaporator reaches the setpoint temperature (T11-sp). - increasing the speed of rotation of the compressor to its maximum speed; - determining a modified setpoint temperature (T15-sp3) of the third element that is greater than the first setpoint temperature (T15-sp1) so that the temperature of the second element at the outlet of the first evaporator tends toward its setpoint temperature (T11-sp); - adjusting the opening diameter of the second expansion device so that the temperature of the third element at the outlet of the second evaporator reaches a modified setpoint temperature (T15-sp3), until the temperature of the second element at the outlet of the first evaporator reaches the setpoint temperature (T11-sp).