Superheat Too High (15°C) → Capacity Loss & Discharge Overheating

Question

Superheat Too High (>15°C) → Capacity Loss & Discharge Overheating

Accepted Answer

TXV under-opening — spring over-tightened or sensing bulb refrigerant leakage. Check: Measure suction and discharge pressures simultaneously; if suction below normal, check TXV opening or refrigerant shortage first What to do: Turn TXV adjustment screw CCW 1/4 turn at a time → wait 2 min → re-measure SH → stop when 5–8°C range reached TXV filter (strainer) clogged with debris → reduced refrigerant flow. Check: Compare TXV inlet and outlet temperatures — >1°C difference across strainer indicates clogging What to do: Remove TXV strainer → blow clean with dry nitrogen in reverse direction → reassemble → verify SH after operation EEV step motor failure or valve coil open circuit → valve stuck at minimum opening. Check: Send manual force-open command from EEV controller → if opening doesn't change, step motor or coil defective What to do: Measure coil resistance vs manufacturer spec → replace coil if defective → replace EEV assembly if step motor failed

Superheat Too High (>15°C) → Capacity Loss & Discharge Overheating

Likely causes

TXV under-opening — spring over-tightened or sensing bulb refrigerant leakage

TXV filter (strainer) clogged with debris → reduced refrigerant flow

EEV step motor failure or valve coil open circuit → valve stuck at minimum opening

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