The A/C compressor installed in the Toyota cars on sale in the Japanese market since August 1983, has adopted the variable displacement control method, and as a result, both comfort and power saving have been obtained. The compressor called “Two-stage variable displacement type A/C Compressor (10P-V)” is based upon the swash-plate type compressor, with ten cylinders to the front and rear of the cylinder block, and is constructed with a two mode choice. In the first, high load cooling is carried out (100% displacement) with all the cylinders operating. In the second, low load cooling is carried out (50% displacement) with the five cylinders in front operating while the discharge valves of the five rear cylinders are unloaded. From various on-vehicle tests we carried out, it was found that the compressor's power consumption could be reduced about 30% annually and also, the level of comfort could be maintained at approximately the conventional level through the automatic switching of the capacity between 100% and 50% depending on the required cooling capability.IN RECENT YEARS, there has been a change in the trend of automobile technological development, partly as a result of the oil price hikes of the 1970's, away from the pursuit simply of high performance towards the search for performance and power saving. With regard to the automobile A/C device, the situation is the same. It has become an important point in the 1980's that products achieving down sizing, weight reduction, power saving and improved NVH should be developed. For the compressor, which is the heart of the automobile A/C system, down sizing, weight reduction and power saving have been achieved. In order to achieve power-saving operation while at the same time maintaining comfort and providing optimum control of the compressor capacity, thereby going along with recent market trends and coping with fluctuations in cooling load, the concept of a variable capacity compressor was born and research and development of such a compressor carried forward. We have introduced to the Japanese market a “10P-V Compressor” which is the variable displacement compressor. It is installed in the Toyota Crown that has been on sale since August 1983. This paper describes the development process of this 10P-V compressor.