When charging a system with refrigerant, the technician should put the low- and high-side service valves in which position?

The correct choice for charging a refrigerant system involves placing the low- and high-side service valves in the mid-position. This position allows the refrigerant to flow effectively into the system while also ensuring that both the high and low sides of the system can equalize pressures without backflow or restriction.

In the mid-position, the service valves are partially open. This setup permits the technician to monitor refrigerant flow and pressure while charging. It balances the system’s pressure levels, helping to prevent potential damage to components like the compressor, which could occur if there is an unbalanced charge or improper pressure differentials.

When compared to the other configurations, the mid-position provides a controlled and safe method for charging. For instance, a back-seated position would prevent refrigerant flow and is used for service work where the valves are closed. The front-seated position would allow full flow but is not advisable for charging as it can lead to overcharging or system damage. The ability to regulate the operation effectively is crucial when introducing refrigerants, making the mid-position the ideal choice for this procedure.