Chevrolet Repair: adding freon, buick lasabre, internal thread

Question
where is the valve for adding freon to my 1997 Buick lasabre 3.8 engine, I can only locate the one at the fire wall and it has a internal thread connection and does not work with my gage kit

Answer
Hi Jim...follow the A/C lines from the compressor... the low pressure side is the one you want to use...it will be the one that goes to the bottle like looking condenser near the firewall. if you are using a red tech kit the hose will only connect to the low pressure hose so you can't mix it up. The connection should be close to that bottle...hope this helps