Since 20 Years CoolTool is used for refrigeration system design and calculation. In that time more and more customers wished to have a system to measure and analyses System, and to calculate them with the reliable algorithms from CoolTool. To consider these wishes from the customer side the new release contains “CoolTool – DiaGnostics” – a combined hard- and software solution to optimize any kind of refrigeration circuit. The hardware is divided into three basic building blocks. The “CoolTool DiaGnostic Masterbox” is the heart of the system. It is collecting the data from the other components, with or witout a notebook. As a stand alone system, controlled by a touchscreen, is writing the measurements on a removeable SD-Card. Or it is send ing the information via USB Port to a notebook. Eight PT1000 Sensors and further required pressure sensors could be connected to the Masterbox directly. The second building block, named “CoolTool DiaGnostic Sputnik”, was developed to take distant heat exchangers into consideration. Up to a distance of 200m it is collection several Temperature and Pressures. And finally it is sending these information to the Masterbox. The third building block, “CoolTool DiaGnostic Powermeter” is complementing the system. Is it collecting the electrical data from compressors, fans or solenoide valves and sending it to the Master Box or to a Sputnik. All these buiding block are running up to 8 or 24 hours independent from power supply with an akkumulator. The DiaGnostic Software is calculating the recorded measurements. Like in the other modues of CoolTool, all existing information can be used for the final diagnostic of the system. There are internal links, for e.g. to the comprehensive database with more than 25.000 parts. So it is easy to selection the a compressor from the database and calculate his capacity with the measured points. The results are given in reports, charts for COP, efficency, capacity and also in a h, log p – Diagram. If a notebook is connected to the Masterbox, all calculation can be displayed in real time. As an example is it possible to calculates the real pressure drop of a suction line in real time and print it out in a chart. Already with the CoolTool DiaGnostic Basic Package all compact applications can be captured and calculated. The CoolTool DiaGnostic Standard Package is offering the possibility to consider external components for e.g. in Supermarkets or in Industrial Application. And it is giving a sophisticated solution to the user to make any kind of Diagnostic inside these systems. It is following the basic CoolTool Philosophie to enable small tasks in a fast and easy way. And also offering an efficient system to solve bigger and extensive labor.