Maintenance cycles and common faults for Hitachi DA65PHDG-D1Y2, AA50PHDG-D1Y2, and AA55PHDG-D1Y2 DC inverter scroll compressors:I. Maintenance Cycle1. Per-Shift Maintenance (Every 8 hours)
Check and eliminate oil, gas, and water leaks.
Check oil levels in the lubricating oil reservoir, crankshaft case, and hydraulic cylinder.
Check the cooling water tank level, jacket water temperature, and engine exhaust temperature.
Check for abnormal operation and vibration in all parts of the compressor.
Check fuel gas pressure, compressor suction/discharge pressure, and temperature.
2. Weekly Maintenance (150 hours)
Check the oil level in the lubricating oil reservoir and top up as needed.
Check for looseness in the bolts connecting the power cylinder and the frame.
Clean the air filter element (cleaning should be performed immediately if the compressor is subjected to heavy wind/sand conditions).
3. Monthly Maintenance (700 hours)
Check the cooling water tank level and top up as needed.
During shutdown, drain accumulated oil from the scavenging chamber and the crosshead slideway oil sump.
Check the pressure drop across the fuel gas filter/separator (should be less than 0.0344 MPa).
Apply lubricating grease to the cooler bearings, water pump bearings, and fuel injection valves.
Check the tension and wear condition of drive belts.
4. Regular Replacement Items
500 hours: First oil change after the break-in period for new machines; replace air filter element, oil-gas separator element, and oil filter.
2000 hours: Replace air filter element and oil filter; apply dedicated grease to the main motor bearings.
3000 hours: Replace lubricating oil; replace the oil-chlorine separator element.
4000 hours: Inspect the thermostat valve, pressure switches, cooling fan, and oil/gas line connections.
II. Common Faults and Causes1. Compressor Overheat ProtectionManifestation: Discharge temperature too high, top temperature protection activated, current protection trip. Causes:
Insufficient refrigerant causing high discharge temperature.
Blocked capillary tube or electronic expansion valve.
Dirty outdoor condenser or poor ventilation.
Low outdoor fan speed (capacitor degradation or motor coil short circuit).
System contamination causing coil damage and short circuits.
Winding enamel damaged during the manufacturing process.
Overloading leading to premature coil aging and burnout.
Frequent compressor cycling causing oil starvation and insufficient lubrication.
3. Crosshead Snap Ring BreakageManifestation: Compressor runs but cannot build up pressure differential, accompanied by abnormal noise or lock-up. Causes:
Unbalanced starting pressure (often occurs when starting immediately after refrigerant charging).
Insufficient oil return or inadequate lubrication in the system.
Compressor high temperature causing low oil viscosity.
4. Scroll Plate WearManifestation: Plating, rust, or abnormal wear on mechanism surfaces. Causes:
Insufficient system vacuum or excessive moisture content in the refrigerant.
Oxide scale or excessive dirt/contaminants in pipelines during installation.
Insufficient oil return or inadequate lubrication in the system.
5. Excessive NoiseManifestation: Undesirable noise during compressor operation. Causes:
Noise from welding defects (motor rub, scroll noise).
Poor control of system contaminants.
Insufficient lubrication after a period of operation.
6. High Discharge TemperatureManifestation: Compressor discharge temperature rises too high shortly after starting; slight signs of overheating on scroll plate surface. Causes:
Poor ventilation around outdoor unit.
Refrigerant leak or insufficient charge.
Reversing valve cross-leakage.
Blocked system filter or electronic expansion valve.
7. System Pressure Differential Not EstablishedManifestation: Compressor runs but cannot build up pressure differential. Causes:
Incorrect compressor U, V, W phase wiring (reversed phase sequence).
System blockage or leak.
III. Maintenance Precautions
Lubrication Oil Management: Use genuine SUNISO 4GSD refrigeration oil. Maintain oil level between the minimum and maximum marks. Excess oil affects separation efficiency, while insufficient oil affects lubrication and cooling performance.
System Cleanliness: Always check oil quality before replacing a compressor. If the oil is black, has an odor, or contains significant debris, it is necessary to replace the refrigerant, drier filter, oil separator, and accumulator.
Electrical Safety: Check that the power supply voltage and phase sequence are correct. Ensure all protective devices (current, pressure, temperature) are securely and reliably connected.
Leak Testing Requirements: Leak testing must be performed using nitrogen or refrigerant. Never use oxygen or flammable gases, as this can cause an explosion.
Refrigerant Charging: Liquid refrigerant must be charged from the high-pressure side. Only gaseous refrigerant may be slowly charged from the low-pressure side. The charge amount must strictly follow the air conditioner's specifications.
With regular maintenance and timely fault resolution, the service life of these three Hitachi DC inverter scroll compressors can exceed 20 years.
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