The book discusses the physical foundations, principles of operation and features of the most common air conditioning systems at present - systems with surface air coolers. Physical properties and processes are described, without knowledge of which it is difficult to understand how modern air conditioning systems work. The basics of refrigeration technology are presented in an accessible form.The basic concepts related to air conditioning systems are considered. The basics of calculations of surface air coolers are stated. Practical examples of calculations are given. Modern comfort air conditioning systems with water and freon surface air coolers (chiller-fan coil systems, split and VRF systems) are considered in detail. Recommendations are given for the selection of equipment for these systems.The book is intended for specialists in the design of air conditioning systems, students of technical educational institutions, as well as everyone who wants to get acquainted with modern air conditioning systems. The book will also be useful to specialists involved in the installation and maintenance of the systems in question.