Experimental densities in the compressed liquid phase are reported for 1,1,1,2-tetrafluoroethane (HFC-134a), triethylene glycol dimethylether (TriEGDME) and six of their mixtures from 293.15 to 373.15 K and at pressures up to 60 MPa. From the experimental results. we have analysed the volumetric behaviour of HFC-134a+TriEGDME. In almost all the measurement range, the density of the refrigerant is greater than that of the polyether. Furthermore, above 333.15 K the densities of the mixtures display a crossover phenomenon with composition. The excess volumes are strongly negative and asymmetrical towards high refrigerant concentrations, becoming more negative when the temperature increases and the pressure decreases.