After a system cleanup the system should be charged:

After a system cleanup the system should be charged:

• A. By weight.
• B. By pressure only.
• C. By experience-based estimate.
• D. By volume of refrigerant added.

Answer: (A)

Charging by weight is the best approach because the total refrigerant charge, as specified by the system design, is a fixed mass. Weighing gives you an exact amount to add, ensuring the system ends up with the correct quantity regardless of other variables. Pressure readings can be misleading since they vary with ambient temperature, superheat, subcooling, and the system’s current state, so the same pressure doesn’t guarantee the same total charge. Volume isn’t reliable either, because refrigerant density changes with temperature and pressure, so the amount by volume can correspond to different masses. After a system cleanup, returning the system to its designed charge is essential, which is why you use a scale and track the tare weight of the cylinder to determine precisely how much refrigerant was added.

Charging by weight is the best approach because the total refrigerant charge, as specified by the system design, is a fixed mass. Weighing gives you an exact amount to add, ensuring the system ends up with the correct quantity regardless of other variables. Pressure readings can be misleading since they vary with ambient temperature, superheat, subcooling, and the system’s current state, so the same pressure doesn’t guarantee the same total charge. Volume isn’t reliable either, because refrigerant density changes with temperature and pressure, so the amount by volume can correspond to different masses. After a system cleanup, returning the system to its designed charge is essential, which is why you use a scale and track the tare weight of the cylinder to determine precisely how much refrigerant was added.