The suction schrader valve is pointing straight up on a line just forward of the brake booster. As someone else said, you should use gauges. The valve out in front to the left of the radiator is on the discharge side of the comp. Don't connect a refrig. can to high pressure. It could blow up in your hand. When adding refrig. be sure that the ambient is > 80 deg. If it is in the 90s, I would pull the condenser fan plug off the head sensor to cause the fan to run during charging.