R-Pro › Field cases › Freezers & ultra-low temperature

Moisture Contamination in Cold Storage System

Likely causes

Insufficient system evacuation before refrigerant charging

Check: Check sight glass moisture indicator color — green = normal, yellow = moisture warning. Check for intermittent EEV blockage symptoms (load drops suddenly then recovers)

What to do: Replace filter drier (minor moisture). Severe moisture: recover all refrigerant → flush with dry nitrogen → evacuate to ≤500 microns for 24 hours → recharge by weight

Moisture in refrigerant charge or piping left open to atmosphere

Check: Check refrigerant charge records — verify use of certified refrigerant. Confirm nitrogen purge and sealing was done after piping work

What to do: Recover all refrigerant → flush with dry nitrogen → evacuate → recharge with certified refrigerant by weight. During piping work, always nitrogen-purge and cap both ends

Faulty compressor crankcase seal

Check: During shutdown, if suction side drops below vacuum (0 bar), a faulty seal can draw in ambient moisture. Check oil color (milky white = moisture contamination)

What to do: Check crankcase heater installation and operation. Replace seal. After oil full replacement, perform acidity test to confirm within normal range

Field tip

Moisture reacts with refrigerant to form acid, causing internal corrosion and insulation breakdown in the compressor. Always include sight glass moisture indicator in inspection routine. Replace filter drier immediately when it turns yellow.

All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.

Open R-Pro →

Related cases