Look for:
* A smaller fitting: The low-pressure port is usually smaller than the high-pressure port.
* A service port cap: This cap is usually blue (though not always). The high-pressure port cap is usually red. *However, rely on the size of the fitting more than the color.*
* Location near the drier/accumulator: The drier/accumulator is usually located near the firewall on the passenger side of the engine compartment.
Caution: If you are not experienced with automotive AC systems, it is highly recommended that you take your vehicle to a qualified technician for AC recharge. Improper handling of refrigerants can be dangerous.