How to know when enough freon 1996 honda civic hatchback?

How to know when enough freon 1996 honda civic hatchback?

The system must be evacuated and filled by weight. The video below shows how it can be done at home, but I prefer to have a professional do it. Getting it wrong by a few ounces can't be seen in the pressure readings but can have serious effects on the life of the compressor.

Use of Freon is against Federal EPA Law.
You need to use a substitute, You are required to Capture any Freon in the system.
Only a Professional is supposed to work on a Freon System.