Blocked A/C?

The sight glass should be running clear if the system is fully charged. If you are not getting cooling then you need to start with pressure tests to determine if you have a good compressor or system failure. If the expansion valve is bad you can have good charge and no to low cool. You can also have plugged filter/dryer as additional culprit. These are the most likley spots although a plugged condensor, evaporator, or internally collapsed hoses are also possible.