A positive fluid displacement apparatus, comprising: a) at least one orbiting scroll member with a first end plate having a first involute wrap affixed to a base surface of said first end plate, an orbiting bearing hub affixed to the surface of said first end plate opposite to said first involute wrap and three equally-spaced peripheral portions on said first end plate; b) at least one stationary scroll member with a second end plate having a second involute wrap affixed to a base surface of said second end plate of said stationary scroll member, said second involute wrap engaged with said first involute wrap of said orbiting scroll member, wherein when said orbiting scroll member orbits with respect to said stationary scroll member the flanks of said engaging wraps along with said base surface of said first end plate of said orbiting scroll member and said base surface of said second end plate of said stationary scroll member define moving pockets of variable volume and zones of high and low fluid pressures; c) a rotatable drive shaft arranged to drive said orbiting scroll member to experience orbiting motion with respect to said stationary scroll member; d) a main housing supporting said stationary scroll member; e) a base housing supporting said drive shaft within a central portion of said base housing; f) a motor housing supporting a motor stator; g) said main housing is integrated with a main housing shell by cooling fins, and air passages are formed between said main housing shell, said main housing and said cooling fins; h) said base housing is integrated with a base housing shell by cooling fins, and air passages are formed between said base housing shell, said base housing and said cooling fins; i) said motor housing is integrated with a motor housing shell by cooling fins, and air passages are formed between said motor housing shell, said motor housing and said cooling fins, characterised in that said positive fluid displacement apparatus comprising: j) a first cooling air channel including said air passages in said main housing shell linked in series with said air passages (326, 328) in said base housing shell and said motor housing shell to form a unidirectional axial cooling air channel; and k) a cooling fan drawing cooling air through said first cooling air channel. a) at least one orbiting scroll member with a first end plate having a first involute wrap affixed to a base surface of said first end plate, an orbiting bearing hub affixed to the surface of said first end plate opposite to said first involute wrap and three equally-spaced peripheral portions on said first end plate; b) at least one stationary scroll member with a second end plate having a second involute wrap affixed to a base surface of said second end plate of said stationary scroll member, said second involute wrap engaged with said first involute wrap of said orbiting scroll member, wherein when said orbiting scroll member orbits with respect to said stationary scroll member the flanks of said engaging wraps along with said base surface of said first end plate of said orbiting scroll member and said base surface of said second end plate of said stationary scroll member define moving pockets of variable volume and zones of high and low fluid pressures; c) a rotatable drive shaft arranged to drive said orbiting scroll member to experience orbiting motion with respect to said stationary scroll member; d) a main housing supporting said stationary scroll member; e) a base housing supporting said drive shaft within a central portion of said base housing; f) a motor housing supporting a motor stator; g) said main housing is integrated with a main housing shell by cooling fins, and air passages are formed between said main housing shell, said main housing and said cooling fins; h) said base housing is integrated with a base housing shell by cooling fins, and air passages are formed between said base housing shell, said base housing and said cooling fins; i) said motor housing is integrated with a motor housing shell by cooling fins, and air passages are formed between said motor housing shell, said motor housing and said cooling fins, characterised in that said positive fluid displacement apparatus comprising: j) a first cooling air channel including said air passages in said main housing shell linked in series with said air passages (326, 328) in said base housing shell and said motor housing shell to form a unidirectional axial cooling air channel; and k) a cooling fan drawing cooling air through said first cooling air channel.