A compressor comprising: a shell (54, 56) defining a first pressure region and a second pressure region; a first scroll member (94, 294) disposed within said shell (54, 56) and including a first end plate (108, 308) and a first scroll wrap, said first end plate (108, 308) defining a discharge passage (112, 312) in communication with said second pressure region; a second scroll member including a second end plate and a second scroll wrap, said second scroll wrap meshingly engaging said first scroll wrap to define a compression chamber therebetween; and a seal assembly (44, 244) defining a biasing chamber (120, 320) and surrounding said discharge passage (112, 312) and fluidly separating said first and second pressure regions from each other, said biasing chamber (120, 320) containing fluid biasing said first scroll member (94, 294) toward said second scroll member, said seal assembly (44, 244) including a first sealing member and a second sealing member, said first sealing member restricting communication between said biasing chamber (120, 320) and said second pressure region when a first fluid pressure within said second pressure region is higher than a second fluid pressure within said biasing chamber (120, 320), said first sealing member and said first scroll member (94, 294) defining a leakage path therebetween when said first fluid pressure is lower than said second fluid pressure, said second sealing member fluidly separating said biasing chamber (120, 320) and said second pressure region when said first fluid pressure is lower than said second fluid pressure; characterized by: a valve member in communication with said biasing chamber and movable between a first position restricting communication between said biasing chamber and said first pressure region and a second position allowing communication between said biasing chamber and said first pressure region, wherein said valve member moves from said first position to said second position in response to a fluid-pressure differential between said first pressure region and said biasing chamber reaching a predetermined magnitude. a shell (54, 56) defining a first pressure region and a second pressure region; a first scroll member (94, 294) disposed within said shell (54, 56) and including a first end plate (108, 308) and a first scroll wrap, said first end plate (108, 308) defining a discharge passage (112, 312) in communication with said second pressure region; a second scroll member including a second end plate and a second scroll wrap, said second scroll wrap meshingly engaging said first scroll wrap to define a compression chamber therebetween; and a seal assembly (44, 244) defining a biasing chamber (120, 320) and surrounding said discharge passage (112, 312) and fluidly separating said first and second pressure regions from each other, said biasing chamber (120, 320) containing fluid biasing said first scroll member (94, 294) toward said second scroll member, said seal assembly (44, 244) including a first sealing member and a second sealing member, said first sealing member restricting communication between said biasing chamber (120, 320) and said second pressure region when a first fluid pressure within said second pressure region is higher than a second fluid pressure within said biasing chamber (120, 320), said first sealing member and said first scroll member (94, 294) defining a leakage path therebetween when said first fluid pressure is lower than said second fluid pressure, said second sealing member fluidly separating said biasing chamber (120, 320) and said second pressure region when said first fluid pressure is lower than said second fluid pressure; characterized by: a valve member in communication with said biasing chamber and movable between a first position restricting communication between said biasing chamber and said first pressure region and a second position allowing communication between said biasing chamber and said first pressure region, wherein said valve member moves from said first position to said second position in response to a fluid-pressure differential between said first pressure region and said biasing chamber reaching a predetermined magnitude. a valve member in communication with said biasing chamber and movable between a first position restricting communication between said biasing chamber and said first pressure region and a second position allowing communication between said biasing chamber and said first pressure region, wherein said valve member moves from said first position to said second position in response to a fluid-pressure differential between said first pressure region and said biasing chamber reaching a predetermined magnitude.