I've got a Chrysler Concorde LXI, 1999. Has over 110,000 miles on it. The AC doesn't do as well as it use to. I want to fix it myself but the manual doesn't give much info other than to call a repair shop. I went to local automotive store who suggested using R-134a synthetic A/C booster. Directions say to connect the cannister to the vehicle A/C los-side service port. I can't see to locate that and the owners manual doesn't specify. Any ideas?