To perform a Controlled Refrigerant Level Check, which method should be used?

The method of performing a Controlled Refrigerant Level Check using a gauge manifold while running the unit in high-speed cool at a 0°F box temperature and a discharge pressure equivalent to a 100°F ambient is correct because it creates conditions that are optimal for accurately assessing the refrigerant level in the system.

When a technician runs the unit under these specified high-speed cool conditions, they can closely monitor the refrigerant pressures and temperatures to ensure that the refrigeration cycle is functioning correctly. The 0°F box temperature simulates real operational conditions under which the system is expected to perform, ensuring that the refrigerant level can be gauged accurately without the influence of varying box temperatures that could potentially skew the readings.

Checking for liquid in the sight glass at this point gives a clear indication of the refrigerant level; if the system is appropriately charged, the sight glass should be clear. This method helps in pinpointing any deficiencies in the refrigerant level, ensuring optimal efficiency and cooling capacity of the unit.

In contrast, the other methods either do not provide appropriate temperature and pressure conditions for an accurate assessment or involve unnecessary complexity, thus making them less efficient for the intended purpose of a Controlled Refrigerant Level Check.