Neutron and gamma radiography measurements have been performed on absorption and compression type refrigerators. Both neutron and gamma radiation were obtained simultaneously from a thermal channel of the 8 MW ASTRA reactor of the Austrian Research Centre Seibersdorf. Radiography images were converted into light by neutron and gamma sensitive converter screens, detected by high sensitivity TV camera, displayed on a monitor, stored by S-VHS recorder and for further analysis a QUANTEL image processing system was used. Characteristic features or absorption aggregates were visualized during different conditions of working processes. Operating time, pressure, temperature, flow velocity, power consumption were measured and recorded as well. It was possible to detect the critical parts of the system responsible for breakdown in operation under extreme conditions. The behaviour of lubrication and cooling oil was observed for compression type refrigerators. The critical extent of foaming was determined before it caused troubles in functioning. Visualization together with a detailed knowledge of the working processes provide an effective tool for manufacturers to improve their products