A heat exchanger, in particular a chiller, includes a heat exchanger block with a first fluid duct for a refrigerant and a second fluid duct for a coolant, an inlet and an outlet for the refrigerant, which are formed at a connecting flange and which are fluidically connected to the first fluid duct, a sensor for detecting a measured variable of the refrigerant, and an electronic expansion valve arranged in the inlet including an integrated regulating unit, wherein the expansion valve regulates a flow rate of the refrigerant in the inlet as a function of the detected measured variable. The sensor and the regulating unit are connected via a cable to transfer data. A port is formed at the expansion valve. The cable is further secured releasably or non-releasably in the respective port at the expansion valve. In addition, a method for controlling or regulating the heat exchanger is provided.