The present study concerns p-T-x phase equilibria measurements involving two working fluid pairs (refrigerant + organic solvent), namely, 1,1,1,2-tetrafluoroethane (R134a) + N,N-dimethylacetamide (DMA) and, 1,1,1,2-tetrafluoroethane + N-methyl-2-pyrrolidone (NMP), using the static analytic method at temperatures varying between 303 and 353 K. The experimentally measured data were successfully correlated using the Peng-Robinson equation of state (PR-EoS) in combination with Huron-Vidal mixing rule, and the nonrandom two -liquid activity coefficient model (NRTL), contrarily to the predictive Soave-Redlich-Kwong (PSRK) group contribution equation of state which failed to reproduce accurately enough such data.