In the vapour compression plants possible leaks can vary the composition of a zeotropic refrigerant mixture. The main aim of this paper is to verify experimentally if the plant performances are restored with a proper recharge, when leaks are imposed. As for the R407C mixture the percentage of the less volatile component (R134a) increases, while the percentage of the more volatile components (R32 and R125) decreases when leaks occur. The experimental tests have been realized determining refrigerant leaks from the liquid receiver placed at the condenser outlet and measuring the properties in steady state condition. The recharge is realized in different ways: with R407C, with R134a and R410A or with R32 R125 and R134a. The different solutions are then compared from the economical point of view, in terms of COP, refrigeration power and air temperature at the evaporator outlet, adopting an iteration method. This method determines the real composition of a zeotropic mixture working in a compression plant, when only the temperature and pressure values at the expansion valve inlet and outlet are known.