Compressor having capacity modulation system

A compressor comprising:

• a housing,
• a first scroll member supported within said housing and including a first end plate, a first spiral wrap extending from a first side of said first end plate, and a first passage extending from said first side of said first end plate to a second side of said first end plate generally opposite said first side;
• a second scroll member supported within said housing and including a second end plate having a second spiral wrap extending therefrom and meshingly engaged with said first spiral wrap to form a series of compression pockets operating at an intermediate fluid pressure between a suction pressure and a discharge pressure, said first passage being in communication with one of said compression pockets;
• a seal assembly engaged with said housing and said first scroll member and defining an axial biasing chamber in communication with a first of said compression pockets;
• and
• a modulation plate overlying said second side of said first scroll member and located axially between said axial biasing chamber and said compression pockets and within an outer perimeter of said axial biasing chamber, said modulation plate secured within said housing for radial displacement between first and second positions, said modulation plate isolating said first passage from communication with a suction pressure region of the compressor when in the first position and providing communication between said first passage and said suction pressure region when in the second position.