If this system hasn't been open, it sounds as if you need to add more freon. If it has been opened it sounds as if there is some air in the system. 150 isn't near high enough. If there is air in the system it will be hot on the high side and cool on the low but will not chill. If you are sure there is no air(caused by not purging gauge lines when hooking up gauge hoses; second caused not fully evacuating the system before charging it) then add freon. Also check your pressures with engine running at 1500 rpm.