This is true on larger refrigeration systems that use expansion valves and receiver tanks, as long as is not over serviced. But it is false when applied to most small 12-volt units with capillary tubes. These units are precharged by the manufacture with a specific volume of refrigerant any loss during assembly or loss due to leakage means loss of performance. In the field servicing is difficult even for an experienced service technician. The volume of refrigerant for each of these small units will vary from 1.8 to 4 ounces.

Field Service technicians rarely have the equipment to service a system by volume and must adjust volume by monitoring  suction pressure. I have found that for best results adjustments to refrigerant level can only be done with a warm box and the adjustment must be done in the first 15 minutes of operation. After 15 minutes the refrigerant starts to cool were by lowering the suction pressure.  

BACK