R-Pro › Field cases › Refrigeration systems
Refrigerant Overcharge or TXV Over-opening
Likely causes
Refrigerant overcharge (subcooling >10°C)
Check: Measure subcooling: condenser outlet temp − condensing sat. temp (normal 5–8°C, overcharge >10°C)
What to do: Measure subcooling: condenser outlet temp − condensing sat. temp (normal 5–8°C, overcharge >10°C) → If subcooling is normal, the issue is TXV superheat setting → Adjust TXV screw clockwise in 1/4-turn steps (raises superheat) → If overcharged, recover excess refrigerant
TXV adjustment spring under-tension (superheat set too low)
Check: If subcooling is normal, the issue is TXV superheat setting
What to do: If subcooling is normal, the issue is TXV superheat setting → Adjust TXV screw clockwise in 1/4-turn steps (raises superheat) → If overcharged, recover excess refrigerant
High suction pressure and frost on suction line indicate overcharge or TXV over-opening. Measure subcooling and superheat. Superheat below 3°C risks liquid slugging. Do not set below 5°C.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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