The invention relates to a method for controlling a heating or cooling system (1) comprising a heat exchanger (3), a valve (4) arranged to control the flow of a heating or cooling fluid through the heat exchanger (3), at least one temperature sensor (5, 9) arranged to measure a temperature response to a change in the opening degree of the valve (4), a control unit (8) arranged to control the opening degree of the valve (4) as well as to receive temperature measurements from the at least one temperature sensor (5, 9). Task of the invention is to provide an improved control method for such a heating or cooling system (1). According to the invention the task is solved by a method comprising the steps:
a) the control unit (8) stores at least one working point comprising an opening degree of the valve (4) and a corresponding expected temperature,
b) the control unit (8) provides a chosen working point to the valve (4),
c) after a working point has been used for a predetermined time period the at least one temperature sensor (5, 9) provides a temperature measurement to the control unit (8),
d) if the measured temperature does not match the expected temperature derived from the working point, the control unit (8) adapts the currently used working point by changing the stored opening degree.