There is a working fluid for a heating and cooling. The fluid is a blend of from about 1% to about 98% by weight 1,1,1,2,3,3,3-heptafluoropropane, from about 1% to about 98% by weight 1,1,1,3,3,3-hexafluoropropane, and from about 1% to about 98% by weight 1,1,1,2-tetrafluoroethane. The 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,3,3,3-hexafluoropropane, and 1,1,1,2-tetrafluoroethane are from about 90% or more by weight of the blend. There are also an apparatus that uses the blend and methods for heating and cooling using the blend.