Control System for a Heating System and Method for Operating a Heating System

A control system and method for a heating system of an electric vehicle or hybrid vehicle is embodied such that when there is a heating request for a passenger compartment of the vehicle, a heating mode is set in order to heat the passenger compartment by heat from a heating circuit. In a mixed mode, excess heat in the heating circuit is output to the surroundings via a surroundings cooler in a cooling circuit, or in an excess mode it is retained in the heating system, in order to satisfy a heating request. In the mixed mode, a degree of opening of the heating circuit is set such that only a partial quantity of coolant from the heating circuit is exchanged with the cooling circuit and as a result the excess heat is output to the surroundings. The mixed mode is activated if the excess heat in the heating circuit exceeds a threshold value which is determined in accordance with the external temperature.