The refrigeration system should be stocked with the correct type and amount of refrigerant. The first point to check is the nameplate of the equipment where the manufacturer indicates the type and amount of refrigerant.
The vapor charge applies to small systems, to systems that do not have a liquid register, and finally to final load adjustment when small amounts of refrigerant are to be introduced. The coolant cylinder must be standing.
When the refrigerant charge is correct and the system operates under normal conditions, the liquid line display has a smooth flow of bubble free liquid. The presence of bubbles on the display may indicate:
• Lack of refrigerant in the system;
• Filtration line dryer filter clogged;
• Expansion valve too open or oversized;
• Solenoid valve of clogged or undersized liquid line.
Bubble gauge, does not necessarily mean, lack of coolant in the system. The system that lacks refrigerant will exhibit excessively high superheat and low suction pressure.
