This paper presents the study of refrigerant charge imbalance between A/C mode and HP mode of a mobile reversible system. Sensitivities of cooling and heating capacity and energy efficiency with respect to refrigerant charge are looked into experimentally and numerically. Optimum refrigerant charge level for A/C mode is found to be larger than that for HP mode, primarily due to larger condenser size in A/C mode. Refrigerant charge retention in components at both modes are measured in the lab by quick close valve method. Modeling of charge retention in heat exchangers is compared to experimental measurements. Effect of charge imbalance on oil circulation is also discussed.