Compressor having capacity modulation assembly

A compressor comprising:

• a shell assembly defining a suction pressure region and a discharge pressure region;
• a first scroll member disposed within said shell assembly, said first scroll member including a first end plate defining a discharge passage, a first biasing passage, a first modulation port, and a second biasing passage, and having a first spiral wrap extending from a first side of thereof and an annular hub extending from a second side thereof opposite said first side;
• a second scroll member disposed within said shell assembly and including a second end plate having a second spiral wrap extending therefrom and meshingly engaged with said first spiral wrap to form a suction pocket in fluid communication with said suction pressure region, intermediate compression pockets, and a discharge pocket in fluid communication with said discharge passage, a first of said intermediate compression pockets being in fluid communication with said first biasing passage, a second of said intermediate compression pockets being in fluid communication with said first modulation port, and a third of said intermediate compression pockets being in fluid communication with said second biasing passage;
• a seal assembly engaged with said shell assembly and said annular hub and isolating said discharge pressure region from said suction pressure region;
• and
• a capacity modulation assembly including:
• a modulation valve ring located axially between said seal assembly and said first end plate and being in sealing engagement with an outer radial surface of said annular hub and said seal assembly to define an axial biasing chamber in fluid communication with said first biasing passage, said modulation valve ring being axially displaceable between first and second positions, said modulation valve ring abutting said first end plate and closing said first modulation port when in the first position and being displaced axially relative to said first end plate and opening said first modulation port when in the second position;
• a modulation lift ring located axially between said modulation valve ring and said first end plate and being in sealing engagement with said first end plate to define a modulation control chamber;
• and
• a modulation control valve assembly operable in first and second modes and in fluid communication with said modulation control chamber, said modulation control valve assembly controlling an operating pressure within said modulation control chamber and providing a first operating pressure within said modulation control chamber from said suction pressure region when operated in the first mode to displace said modulation valve ring to the first position and providing a second operating pressure within said modulation control chamber from said second biasing passage when operated in the second mode to displace said modulation valve ring to the second position and reduce operating capacity of the compressor.