The invention provides a compressor with a shut off valve disposed between
the crank case and the suction cavity. The valve is moveable between an
open and closed position in response to the pressure in the discharge
cavity of the compressor. The valve is an on/off valve and is operable
rapidly depressurize the interior of the crank case when the compressor
transitions from a minimum stroke. The valve can define first and second
fluid pathways. The first fluid pathway can be larger than the second
fluid pathway and be selectively opened and closed. The second fluid
pathway can be permanently open and act as a bleed between the crank case
and the suction cavity.