In addition to the info provided by acetc, other factors will impact operating pressures. Insufficient indoor airflow (clogged air filter, clogged evaporator coil, blower not operating, etc.) will typically result in lower than normal pressures. Insufficient outdoor airflow (clogged condenser coil, fan not operating) will cause higher than normal pressures. Assure that you do not have problems in these areas before evaluating system performance.