Pontiac Repair: 1998 Grand Prix GTP, grand prix gtp, gm products

Question
Where is the valve to hook up to so I can recharge the A/C? I read the Haynes but it is for GM products 1988 - 2002 and the pics don't look like my engine. I want to think it is right near the firewall, but the book warns to only hook up to the lower valve? I only saw the one by the firewall. Please Help! Thanks

Answer
the easiet way to find any low side charge port is this: find the compressor, locate the large line and follow that. it will be in the large line ,, think this way small line pressure greater, larger line give it more room to expand and less pressure,, please  if you do not know what you are doing dont kjust dump freon in the system with one of those charge all things from the local save a buck store, too much freon will or can damamge the compressor and the valves there has to be just the right ammout in each system...