Low cabin cooling temp became an issue and proceeded to get worse until no cooling at all. Discovered the clutch fell off a new (not rebuilt) compressor. Under warranty so did the replacement as well as the dryer and low pressure switch. Pulled vacuum for .5 - .75 hr. then recharged weighing out 134A and clutch cycled during process until reaching 22 oz. then watched my gauges start to climb. Low pressure side stopped @ "normal". Hi side should have cycled the clutch off @ about 250 psi but did not and continued climbing to 350 psi before I turned off the system. Changed the hi pressure switch today and ran another test with the same results. If caused by a blockage, where is the most likely place for that to occur and how to go about testing? If not, I'd appreciate suggestions.