A refrigerant condenser assembly for a motor vehicle air-conditioning system, comprising - cooling tubes for conducting a refrigerant, - two collecting tubes for fluidically connecting the cooling tubes, - a collecting tank having an upper top wall and a lower base wall and having a side wall and also having an inlet opening for the introduction of the refrigerant into the collecting tank and an outlet opening for the discharge of the refrigerant from the collecting tank, such that the collecting tank is fluidically connected to the collecting tube and/or to the cooling tubes by means of the inlet and outlet opening (18, 19), the collecting tank comprises an outlet chamber and an ascending tube, and the outlet opening issues into the outlet chamber, and the outlet chamber is connected to the ascending tube, and an accumulator chamber for the refrigerant is formed within the collecting tank and outside the outlet chamber and outside the ascending tube, - preferably, the collecting tank comprises an inlet chamber and a descending tube, and the inlet opening issues into the inlet chamber, and the inlet chamber is connected to the descending tube, and the accumulator chamber is formed outside the inlet chamber and outside the descending tube, - the cooling tubes have a superheat region for cooling the vaporous refrigerant, a condensation region for condensing the refrigerant, and a supercooling region for cooling the liquid refrigerant, wherein the supercooling region is formed above the superheat region and above the condensation region, characterised in that the height of the accumulator chamber is greater, in particular 1.1, 1.2 or 1.5 times greater, than the spacing between the lower base wall and the inlet and/or outlet opening (18, 19), and/or the ratio of the sum of the volume of the inlet chamber, of the outlet chamber, of the descending tube and of the ascending tube to the height of the collecting tank is less than 170 and the inlet chamber is formed as a first inlet annular chamber, and/or the outlet chamber is formed as an outlet annular chamber, between the side wall and a tube piece, and preferably, at least two seals, in particular sealing rings (32, 33, 34), are arranged between the side wall and the tube piece in order to provide sealing between the inlet annular chamber and the accumulator chamber and/or between the outlet annular chamber and the accumulator chamber and/or between the inlet annular chamber and the outlet annular chamber, wherein the interior of the tube piece is part of the accumulator chamber. - cooling tubes for conducting a refrigerant, - two collecting tubes for fluidically connecting the cooling tubes, - a collecting tank having an upper top wall and a lower base wall and having a side wall and also having an inlet opening for the introduction of the refrigerant into the collecting tank and an outlet opening for the discharge of the refrigerant from the collecting tank, such that the collecting tank is fluidically connected to the collecting tube and/or to the cooling tubes by means of the inlet and outlet opening (18, 19), the collecting tank comprises an outlet chamber and an ascending tube, and the outlet opening issues into the outlet chamber, and the outlet chamber is connected to the ascending tube, and an accumulator chamber for the refrigerant is formed within the collecting tank and outside the outlet chamber and outside the ascending tube, - preferably, the collecting tank comprises an inlet chamber and a descending tube, and the inlet opening issues into the inlet chamber, and the inlet chamber is connected to the descending tube, and the accumulator chamber is formed outside the inlet chamber and outside the descending tube, - the cooling tubes have a superheat region for cooling the vaporous refrigerant, a condensation region for condensing the refrigerant, and a supercooling region for cooling the liquid refrigerant, wherein the supercooling region is formed above the superheat region and above the condensation region,