(I) Refrigeration System Failures (Most Critical and Frequent)
Refrigerant Leaks: Aging pipe joints, valve seals, or corroded weld points cause refrigerant loss. Symptoms include slow cooling, abnormal evaporator pressure, and frequent compressor cycling. Directly impacts cooling effectiveness and can severely damage the compressor.
Compressor Failure: Insufficient or degraded lubricating oil, clogged suction filters, or worn valve plates cause abnormal noise, overheating, high discharge pressure, or complete shutdown. This is the “heart failure” of the system.
Heat Exchanger Frosting/Scaling: Excessive frost on evaporators (especially in low-temp storage) or scaling on condensers (due to poor water quality or dusty environments) reduces heat exchange efficiency, decreases cooling capacity, and can increase energy consumption by over 30%.
Expansion Valve/Solenoid Valve Failure: Blockage, sticking, or faulty sensing bulbs cause uneven refrigerant supply. This leads to localized frosting on evaporators and large temperature fluctuations (±2°C or more), affecting stored goods quality (e.g., frozen produce, spoiled meat).
(II) Insulation and Sealing Issues
Damaged Insulation: Cracks at panel joints, moisture-bloated floor insulation, or aged door insulation cause cold loss, increased energy use, and condensation at temperature differentials, leading to structural corrosion.
Deteriorated Seals: Aging, deformed, or damaged door gaskets and excessive door frame gaps allow warm, moist air infiltration. This causes frost/ice buildup inside doors and on floors, increasing cooling load and potentially causing goods to become damp or moldy.
Frost Heave (Floor): Inadequate frost protection for low-temp storage floors or blocked ventilation pipes causes ground moisture to freeze and expand, cracking and heaving the floor, compromising structural safety.
(III) Electrical and Control System Failures
Aging Electrical Components: Burnt contacts on contactors/relays or damaged wire insulation in the high-humidity cold storage environment can cause short circuits, tripping, or even electrical fires.
Faulty Temperature Controls/Sensors: Sensor drift or controller malfunctions cause inaccurate temperature readings (>1°C error) and improper system cycling, preventing precise environmental control.
Drainage System Failure: Clogged defrost drain pipes or damaged heater wires prevent water drainage, leading to ice accumulation and water pooling that affects storage and operation.
(IV) Daily Operation and Management Issues
Improper Goods Stacking: Blocking evaporators or air return vents disrupts airflow, causing significant temperature variations (e.g., warmer areas near doors).
Improper Door Usage: Frequent or prolonged door opening allows massive heat/moisture ingress, increasing cooling load and frost probability.
Lack of Maintenance Records: Absence of detailed logs makes tracking equipment performance and diagnosing faults difficult.
- Targeted Maintenance Solutions (Including Standards & Frequency)
(I) Refrigeration System Maintenance
Refrigerant Leak Prevention & Handling:
Routine Check: Weekly soap bubble test on joints, valves, welds. Monthly pressure logging (Suction: 0.2-0.4MPa, Discharge: 1.2-1.6MPa, adjust per refrigerant).
Solution: Immediately shut down if leak detected; replace seals or re-weld; evacuate and recharge to specified amount. Perform annual comprehensive leak check and refrigerant purity test.
Compressor Maintenance:
Scheduled Service: Change oil (use dedicated refrigeration oil) every 2000 operating hours ; clean suction filter. Inspect valve plates/piston rings every 6 months , replace if needed.
Fault Response: Shutdown for abnormal noise; check bearings/rotor. For overheating, clean condenser, check cooling fans.
Heat Exchanger Maintenance:
Evaporator Defrosting: Manual defrost 1-2 times daily (when frost >5mm). For auto-defrost, weekly check timer/heater; ensure cycle is appropriate (typically every 4-6 hours for 15-20 mins ).
Condenser Cleaning: For air-cooled, monthly rinse fins with low-pressure water (<0.3MPa). For water-cooled, quarterly clean tank/change water (add antifreeze/corrosion inhibitor); annually descale pipes.
Expansion Valve/Solenoid Valve Maintenance:
Routine Check: Monthly observe liquid supply; ensure even frosting downstream. For uneven/no frost, dismantle and clean valve core, check sensing bulb attachment (tight on suction line, insulated).
Scheduled Replacement: Replace expansion valve filter every 2 years . Check solenoid coil operation every 3 years .
(II) Insulation and Sealing Maintenance
Insulation Repair:
Inspection: Quarterly full inspection of panels/doors, focusing on joints/corners.
Solution: Fill cracks with polyurethane foam, seal with foil tape. For wet floor insulation, fix drainage first, then replace material and reapply vapor barrier.
Sealing Optimization:
Door Maintenance: Monthly inspect gaskets; replace if aged/deformed (use low-temp resistant silicone). Adjust hinges for gap <2mm when closed. Install air curtains/soft strip curtains inside doors.
Frost Heave Prevention: For low-temp storage (≤-18°C), monthly check floor vent pipes. Annual floor temp check; add insulation or heating if heave signs appear.
(III) Electrical & Control System Maintenance
Electrical Component Maintenance:
Routine Check: Monthly wipe control cabinet with dry cloth. Every 3 months check wire connections/insulation; tighten terminals.
Moisture Protection: Install dehumidifier in cabinet (maintain humidity <60%). Use components with IP54 or higher rating in humid areas.
Temperature Control & Sensor Maintenance:
Calibration & Check: Calibrate sensors against reference thermometer every 3 months (error ≤±0.5°C). Monthly check controller program, test manual/auto modes.
Fault Response: Recalibrate drifting sensors; replace faulty ones (use PT100 type for low temp). Reset faulty controller to defaults; contact manufacturer if issue persists.
Drainage System Maintenance:
Routine Cleaning: Weekly clear drain pipes (air blow/rod). Monthly check heater wire operation.
Winter Protection: Insulate drain pipes; add heat trace cable to prevent freezing.
(IV) Daily Operations Management
Proper Goods Stacking:
Standard: Keep goods >30cm from evaporators/return vents, >50cm from doors. Stack height must not block sprinklers (if present) or lights; ensure air circulation.
Optimized Door Usage:
Policy: Post “Close Door” signs. Train staff for quick loading (<5 minutes per opening). Install auto-close delay and door-open alarms.
Maintenance Record System:
Content: Daily log temperature (AM/PM), equipment status. Weekly log pressure, current. Document all maintenance/fault repairs with date, details, personnel.
III. Annual Comprehensive Maintenance Essentials (Mandatory Items)
- Complete disassembly, cleaning, and inspection of the refrigeration system (compressor, condenser, evaporator, expansion valve) for wear; replace aged parts.
- Inspect structure (panels, floor, door frames); repair insulation/sealing defects; apply anti-rust treatment to metal parts.
- Fully calibrate electrical control system; test emergency stop and alarm functions; replace aged wires and components.
- Thoroughly clean interior (racks, floor, walls); disinfect with food-grade sanitizer.
- Conduct maintenance staff training on common fault diagnosis and emergency procedures.
