Low-pressure port: The low-pressure port is typically located on the side of the compressor, and it is usually marked with an "L" or "LO" symbol. This is the port that you will use to add refrigerant to the system.
High-pressure port: The high-pressure port is typically located on the top of the condenser, and it is usually marked with an "H" or "HI" symbol. This is the port that you will use to release refrigerant from the system.
To determine which line you should connect your charging hose to, you should follow the instructions in your vehicle's owner's manual. However, in general, if your AC system is low on refrigerant, you will connect your charging hose to the low-pressure port. If your AC system is overcharged with refrigerant, you will connect your charging hose to the high-pressure port.
