Passenger rolling stock is operated in various climatic conditions, calculated outside temperature can vary from -40 to +40 °С. The microclimate parameters permissible for a long stay of people (the longest route is about 6 days) are achieved by installing ventilation, air conditioning and heating systems. Currently, more and more attention is being paid to the safety and comfort of passengers, and the urgent task is to create a climate system that ensures that the air environment in the premises of passenger rolling stock is up to date with all requirements. To ensure safe parameters of the car air environment, it is necessary to increase the influx of outdoor air to 20-35 m3/h per person, which allows achieving a CO2 content of 1000 ppm. It should be taken into account that an increase in the flow of external air and its conditioning leads to an increase in the cost of electricity (in order to fulfill the requirement for the content of CO2, an increase in the power of the heaters by 1.5-2 times is required), and therefore, the cost of transportation. Comparison of sources of additional energy, the use of which can increase the flow of external air into the car with minimal additional loads on the power supply system, showed the greatest efficiency of the installation with a heat pump that uses the heat of the exhaust air to heat the supply air in combination with maintaining air back-up for protection against dust. Proposed technical solution allows to increase the level of comfort in passenger cars with minimal energy costs for air processing and equipment dimensions. The problem of increased hydraulic resistance of the installation is solved by using a beam of transversely streamlined pipes with longitudinal turbulators of a hydraulic boundary layer as the heat exchange surface of the evaporator of the heat pump. This surface will allow to develop a heat exchanger with minimal resistance and thereby get away from the need for forced traction, limiting to a minimum back pressure of 15 Pa.