A heating system for cars is designed as a control circuit with a heater (2) and a controller (1) in a single housing. The heating can be controlled or a parameter determining the heating can be controlled. The controller has at least two linear controllers in parallel. The semiconductor components of the controller are on a common good heat- conducting carrier body, actually a copper plate. The heating elements are heating resistances. The system is used for heating a medium in the heating or cooling circuit of the car, or for space heating.
