known the orbiting scroll element 22 orbits relative to the non orbiting scroll element 24 and the scroll wraps 23 and 25 selectively trap pockets of refrigerant which are compressed toward discharge port 26 a plurality of ports 28 and 30 are formed in the base 31 of the non orbiting scroll element 24 alternately ports 28 and 30 may consist of a pair of single larger ports in the position shown in fig1 ports 28 and 30 are just being uncovered by the orbiting scroll wrap 23 at about the same time as compression chambers 27 and 29 are being sealed from a zone that communicates with suction line 45 as shown in fig2 with continued movement of the orbiting scroll wrap ports 28 and 30 are uncovered and are exposed to compression chambers 27 and 29 which have been closed by the movement of the orbiting scroll wrap 23 to contact the non orbiting scroll wrap 25 as shown in fig3 a first passage 32 communicates with ports 30 and a second passage 34 communicates with ports 28 a crossing passage 36 communicates between passages 32 and 34 a series of plugs 38 close the passages 32 34 and 36 as appropriate a passage 40 communicates crossing passage 36 to a bypass valve 42 which leads to a line 44 leading back to a suction line 45 and to a passage 46 which leads to an economizer valve 48 which communicates with an economizer injection line 50 which is communicated to an economizer heat exchanger 52 or economizer flash tank as shown in fig4 the economizer heat exchanger 52 is positioned just downstream of the condenser 54 of a refrigerant.