Method for controlling a thermal management device of a motor vehicle, said thermal management device having a refrigerant fluid circuit in which a first heat transfer fluid is intended to circulate and being configured to operate in a heat pump mode, said refrigerant fluid circuit having, in the direction of circulation of the refrigerant fluid in heat pump mode: a. - a compressor, b. - a first heat exchanger intended to exchange heat energy directly or indirectly with an internal air flow, c. - an expansion device, d. - a second heat exchanger intended to have an external air flow passing through it, e. said thermal management device also having an electric heating device intended to directly or indirectly heat the internal air flow, f. said control method involving, during a cold start of the thermal management device, the following steps: i. - direct or indirect heating of the internal air flow only by the electric heating device until said internal air flow reaches a target temperature below a comfort temperature determined in relation to a request from a user, and/or until the expiration of a predetermined timer, ii. - when the internal air flow has reached its target temperature and/or the timer has expired, starting up of the compressor so that the refrigerant fluid circuit draws off heat energy from the external air flow at the second heat exchanger and releases said heat energy at the first heat exchanger so that the internal air flow reaches the comfort temperature. a. - a compressor, b. - a first heat exchanger intended to exchange heat energy directly or indirectly with an internal air flow, c. - an expansion device, d. - a second heat exchanger intended to have an external air flow passing through it, e. said thermal management device also having an electric heating device intended to directly or indirectly heat the internal air flow, f. said control method involving, during a cold start of the thermal management device, the following steps: i. - direct or indirect heating of the internal air flow only by the electric heating device until said internal air flow reaches a target temperature below a comfort temperature determined in relation to a request from a user, and/or until the expiration of a predetermined timer, ii. - when the internal air flow has reached its target temperature and/or the timer has expired, starting up of the compressor so that the refrigerant fluid circuit draws off heat energy from the external air flow at the second heat exchanger and releases said heat energy at the first heat exchanger so that the internal air flow reaches the comfort temperature. i. - direct or indirect heating of the internal air flow only by the electric heating device until said internal air flow reaches a target temperature below a comfort temperature determined in relation to a request from a user, and/or until the expiration of a predetermined timer, ii. - when the internal air flow has reached its target temperature and/or the timer has expired, starting up of the compressor so that the refrigerant fluid circuit draws off heat energy from the external air flow at the second heat exchanger and releases said heat energy at the first heat exchanger so that the internal air flow reaches the comfort temperature.