A bypass valve for directing fluid flow, where the bypass valve includes a valve body with a notch in at least one end thereof and a spool seated within the valve body. The spool is rotatable within the valve body. One preferred embodiment of the present invention also includes at least one endcap attached to an axial end portion of the spool, where the endcap includes a protrusion extending thereon for preventing relative rotation between the spool and the valve body when the protrusion is positioned within the notch. A further aspect of the present invention relates to a bypass valve with a valve body including a plurality of ports and a generally cylindrical inner periphery, as well as a spool seated within the valve body, where the spool is rotatable and axially translatable within the valve body. The spool further preferably includes a top seal seated upon a seal seating surface, where the top seal acts in one mode to block a service inlet port, without blocking the other ports, or, in another mode, blocks the service inlet port and the service outlet port, without blocking the other ports.