To effectively find a suspected refrigerant leak on a freezer room evaporator, what should be done?

To effectively find a suspected refrigerant leak on a freezer room evaporator, conducting a leak test of the evaporator with the unit in shutdown is the most appropriate action. When the refrigeration system is not running, it is easier to identify the presence of a leak because the refrigerant is not circulating, allowing for a more accurate assessment. Additionally, this approach can involve techniques such as the use of soap bubbles, electronic leak detectors, or other methods that can help pinpoint the location of the leak without interference from the operational system.

Other methods, such as changing the refrigerant or increasing the compressor pressure, do not directly address the leak detection process and could potentially complicate the situation or introduce additional risks. Performing a thermal scan can provide insights into temperature differentials, but it may not specifically confirm a refrigerant leak as effectively as a targeted leak testing approach. Thus, the focused method of leak testing with the unit in shutdown is the most reliable and effective strategy in this scenario.