The invention relates to a control process for an air conditioning system. The air conditioning system comprises a thermal loop (1) used as a heat pump and an electrical heating device (2). The process calculates a global heating capacity (HCglo) in function of the temperature chosen by the passenger, the speed of the blower and the temperature of the exterior air. Then, the process calculates a heating capacity (HC1) of the thermal loop (1) and compares this heating capacity (HC1) of the thermal loop to the global heating capacity (HCglo). If the global heating capacity (HCglo) is superior to the heating capacity (HC1) of the thermal loop, the process determines a heating capacity (HC2) of the electrical heating device (2). This heating capacity (HC2) of the electrical heating device (2) added to the heating capacity (HC1) of the thermal loop (1) allows to obtain the global heating capacity (HCglo) required in function of the temperature selected by the passenger.