I can't tell the orientation from your pic, but you charge on the side where the larger diameter hose is attached. You might see an "S" or "suction" stamped on the compressor. Should be the side closest to the engine.
When you hit the A/C button, does the engine rpm change? Look at the hub of the compressor-it's the part in front of the pulley. With the A/C engaged, it should be spinning along with the pulley. If it's not moving, you're reading static pressure because the compressor isn't turning. For testing pruposes only, you can hook 12 volts directly to the wire going to the compressor clutch and see what the pressure drops to. You're looking for 20-25 psi.