A method for determining wire connections in a vapour compression system (1) is disclosed. The vapour compression system comprises a compressor, a condenser, an expansion device (2) and an evaporator (3) being fluidly interconnected in a refrigerant path, and two or more sensor devices (7, 8, 9, 10, 11) arranged for measuring variables which are relevant for the operation of the vapour compression system (1). The method comprises the steps of changing an operational setting, e.g. an opening degree of the expansion device (2) for the vapour compression system (1), monitoring variable values, such as temperatures, being measured by at least two sensor devices (7, 8, 9, 10, 11), e.g. arranged at various positions of the vapour compression system (1), in response to said changed operational setting, comparing the measured variable values to expected behaviour of at least one variable measured by a sensor device (7, 8, 9, 10, 11) in response to said changed operational setting, and based on the comparing step, determining at least one wire connection of the vapour compression system (1). The method allows correct wire connections to be established without any special effort from the installing personnel, and without requiring rewiring of the system.