im new to refegiration passed all courses and now its time to start learning one question i kept asking but could not get a answer to is
IS THERE A WAY OF SEEING IF A AIR CON / REF SYSTEM IS UNDER / OVER CHARGED

EXAMPLE CAR AIR CON SYSTEM 134A
LOW SIDE /VACUME PRESURE IS 3BAR HIGH SIDE IS 15BAR IS IT OVER / UNDER CHARGED OR do you have to remove and recharge can any one help ?