During a manual air defrost, operators must ensure they do NOT?

The correct answer centers around the importance of managing liquid refrigerant flow during manual air defrost procedures. When operators are performing a defrost, they should avoid trapping liquid refrigerant within the system, as this could lead to complications such as increased pressure within the refrigerant lines and potential safety hazards.

Trapping liquid can hinder proper system functionality and may lead to inefficiencies or even equipment damage, especially if the defrosting needs to resume and the liquid cannot flow freely back into the compressor. It's essential that operators ensure proper valve management to allow refrigerant to flow correctly without causing unwanted liquid traps, thus maintaining system integrity and operational safety.

Understanding this aspect is crucial for ensuring that the refrigeration system functions optimally and that operators manage conditions effectively during critical procedures like defrosting.