Never - unless there is a leak in system
R134a
You will need to connect your Freon bottle to the low pressure port on your 2002 Chevy Cavalier air conditioning compressor. Release the Freon into the compressor. A Freon recharge kit will come with everything you need and instructions.
100 bucks or so
Connect a Freon bottle to the low pressure port on the top of your air conditioning compressor. Release the Freon into the air conditioning system. A recharge kit will make the process simple.
A 2002 Mitsubishi Lancer requires 26.85 ounces for a complete recharge. The normal freon can has 12 ounces so it would take just a little more than two cans.
Purchase a recharge kit from your local auto parts store. It will come with instructions. Keep in mind if the system is low or empty, it will probably leak out again after you recharge.
A can of freon with the hose and valve connected to the low pressure of the air condition system and squeeze
You add refrigerant at the low pressure port but you do not add Freon. You add R134/134a. If you are having to add refrigerant then you have a leak that needs to be repaired first.
The best way to fix an expansion valve for the A/C system is to replace it. of course then you have to evacuate and recharge with freon.
You will look for the smaller of two ports. The smaller one is the low pressure port. hey usually have a green or blue cap on them.
100-120K miles.
How do I put freon in a 2002 Cadillac deville