A compressor includes an orbiting member and a non-orbiting member mounted relative the orbiting member to define first and second chambers disposed between the orbiting and non-orbiting members. The non-orbiting member forms a seal to generally prevent fluid communication between the first and second chambers when in a first position and breaks the seal to allow fluid communication between the first and second chambers when in a second position. A structure supports the orbiting and non-orbiting members for relative orbital movement therebetween and a time pulsed actuation apparatus is coupled to the structure and configured to selectively break the seal.