NOVELTY - A cooling and warming system comprises cooling unit, warming unit, temperature sensor for detecting device temperature and for delivering to a control unit a temperature signal based on temperatures detected, and pipe system to convey a medium for cooling and warming. The system further comprises reversible pump for moving the medium in the pipe system in first or second opposite direction depending on control signals from the control unit; and one-way valves close to respective cooling unit and warming unit in such a way that the flow through the one-way valves passes either unit.    USE - Cooling and warming system for hybrid (bus, truck, or passenger car) or electric vehicle (claimed) and device comprising direct current (DC)/DC converter and other power electronic converters and electric motors.    ADVANTAGE - The system is robust, of less complexity than present-day systems, and simple, thus inexpensive to make.    DETAILED DESCRIPTION - Cooling and warming system comprises cooling unit, warming unit, temperature sensor for detecting device temperature and for delivering to a control unit a temperature signal based on temperatures detected, and pipe system to convey a medium for cooling and warming so that the device is respectively cooled and warmed. The system further comprises a reversible pump close to the pipe system for moving the medium in the pipe system in first or second opposite direction depending on control signals from the control unit; and one-way valves close to respective cooling unit and warming unit in such a way that the flow through the one-way valves passes either unit, depending on the respective pump direction. The control unit delivers to the pump, on the basis of the temperature signal, control signals to pump the medium in first direction if the device is to be cooled and in second direction if the device is to be warmed.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic block diagram of the cooling and warming system.