I found the port this way. I looked at the diagram on the inside of the hood area on the front. It tells where the serpentine belt track travels and shows the AC is right in the front on the right of the belt track. There are two lines with knobs on them (side by side) coming out of the AC unit. The one that is on the inside is the Low pressure port. It has the slimmer metal tubing.
The 2001 Saturn L200 low pressure port can be found on the air conditioning compressor. The low pressure port will be closest to the front of the engine compartment.
Please visit my BIO page for a link to my Saturn help site. under cooling and a/c you will find a visual reference as to which connector is the low pressure port
The low pressure port on a Saturn I200 is attached to the oil filter, which is directly below the vehicle's engine. The pressure port is directly attached to the fuel rail, and just above the fuel injectors.
The low pressure port on a 1996 Oldsmobile Cutlass is between the compressor and the firewall. It is on the larger hose attached to the compressor.
Under the hood
The 1996 850 doesn't have a high pressure port. Recharging is done through to low pressure side.
The Low Pressure Side port is located on the line coming from the the compressor. It can be identified by the black cap marked LOW.
the low side pressure port is located just off the back of the compressor, the highside is located in the line on the side of the compressor body
The low side service port can be found on top of the air conditioner compressor. The low side service port will have a blue top.
On the line right at the compressor.
The low side port is at the end of the suction hose on the aluminum located where the end bolts up.......
Low pressure port which is the larger hose.