You don't charge by pressure when system is empty. You recharge by vacuuming system, and then introducing the specification amount (weight in oz) of R134a into system. On Accords, 2-14oz cans is usually more than adequate (check under hood for specification amount).
If you're trying to "top-up" a working AC system, it is complicated and requires some experience to get close. A R134a AC manifold gauge set is required to monitor both high side and low side pressures w/ AC On, Max Fan, Recirculate, and engine at 1500-2000 rpm. Car should be in shade. You will also need to measure the air temperature entering the condensor at the front of the vehicle. Allow system to stablize for 5-10 mins. If fully charged the high side pressure should be 2.2-2.5 times air temp (in psi) entering condensor (when compressor is engaged), and low side pressure should about 24-30 psi. So at 100F air temp, pressure should be 220-250 psi high side and low side, 24-28 psi. Vent temps should be 35-45 below cabin air temp (on floor board). Extra charge is introduced through the low side slowly, allowing ac system to stabilize (1-2 mins) before adding more.
Suggest reading an automotive AC repair manual to provide some background and guidance to ac repair. Not difficult, but does require patience and determination.
See you down the ROW
2005 Toyota Matrix
2003 Acura MDX
2006 Acura TSX
2010 Acura TSX