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Subcooling Excessive (>10°C) → High Condensing Pressure & Efficiency Loss (Overcharge Suspected)

Likely causes

Refrigerant overcharge → excess liquid occupies condenser → effective condensing area reduced → high condensing pressure

Check: Subcooling >10°C + condensing pressure above normal + both suction and discharge high + superheat low → almost certain overcharge

What to do: Recover refrigerant 100 g at a time → wait 5 min → re-measure subcooling → stop when 5–8°C reached

Receiver outlet valve partially closed → liquid pools on condenser side

Check: Visually inspect receiver outlet service valve; confirm fully open (back-seated)

What to do: Fully open service valve → run system → recheck subcooling

Condenser fan overspeeding or ambient temp sudden drop → condensing pressure too low → excessive subcooling

Check: Check condenser fan inverter current frequency; inspect fan control logic vs ambient temperature

What to do: Adjust fan inverter floor setting — add logic to reduce fan to ≤50% when ambient ≤20°C

Field tip

Recover refrigerant 100 g at a time slowly — recovering too much at once can trigger low-pressure trip. Wait 5 min after each recovery before re-measuring.

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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