As one of the core components of a cold storage system, the stable operation of a compressor directly affects the efficiency and reliability of the entire refrigeration system. During prolonged use, the compressor may malfunction due to various reasons, affecting its refrigeration effect and even causing damage. This article introduces potential problems with compressors and their possible causes for reference.

1. Compressor fails to start normally:

• Supply voltage is too low.
• Poor contact in the motor circuit.
• Leakage in the discharge valve plate, leading to excessively high pressure in the crankcase.
• Malfunction of the capacity control mechanism.
• Temperature controller out of adjustment or malfunctioning.
• Pressure relay failure.

2. Frequent start-stop of the compressor:

• Leakage in the discharge valve plate, resulting in balance between high and low pressures, and excessively high inlet pressure.
• Excessively small differential in the temperature relay.
• Poor heat dissipation in the condenser, causing excessively high pressure and high-pressure relay actuation.

3. No oil pressure after startup or insufficient oil pressure during operation:

• Oil pump piping leakage or blockage.
• Oil pressure control valve opened too widely or valve core detached.
• Insufficient oil in the crankcase.
• Ammonia liquid in the crankcase, affecting oil pump operation.
• Severe wear on the oil pump, causing large clearances.
• Severe wear on connecting rod bushings, connecting rod small end bushings, and piston pins.
• Oil pressure gauge valve not opened.

4. Excessively high oil pressure:

• Oil pressure control valve closed or opened too narrowly.
• Oil circuit system blocked.
• Oil pressure control valve jammed.

5. Oil pump unable to build pressure:

• Severe wear on oil pump parts, causing large clearances.
• Oil pressure gauge malfunction, pointer not functioning.
• Improper assembly of oil pump components.

6. Lubricating oil in the crankcase foaming:

• Large amounts of refrigerant liquid mixed into the lubricating oil, ammonia liquid evaporates and forms foam when pressure decreases.
• Excessive oil filling in the crankcase, stirring by the connecting rod big end causes foaming.

7. Excessively high oil temperature:

• No water supplied to the crankcase oil cooler.
• Improper assembly of shaft and bushings, causing small clearances.
• Impurities in the lubricating oil, causing bushing wear.
• Shaft seal friction ring installed too tightly or worn.
• Excessively high suction and discharge temperatures.

8. Unstable oil pressure:

• Oil pump sucking in foamy oil.
• Oil circuit not smooth.

9. High oil consumption of the compressor:

• Severe wear on the oil ring, large assembly clearance.
• Oil ring installed backwards, incorrect location of the locking tab.
• Large clearance between the piston and cylinder.
• High discharge temperature, lubricating oil carried away by the airflow.
• Excessively high oil level in the crankcase.
• Malfunction of the automatic oil return valve in the oil separator, oil cannot return to the crankcase automatically.

10. Increased pressure in the crankcase:

• Poor sealing of the piston rings, allowing high-pressure gas to escape into the low-pressure side.
• Insufficient sealing of the discharge valve plate.
• Leakage in the sealing surface between the cylinder liner and block.
• Ammonia liquid entering the crankcase, increasing pressure after evaporation.

11. Failure of the capacity control mechanism:

• Excessively low oil pressure.
• Oil piping blocked.
• Oil piston jammed.
• Improper installation of the tie rod and rotating ring, rotating ring jammed.
• Incorrect assembly of the oil distribution valve.

12. Excessively high discharge temperature:

• High condensation pressure.
• Low suction pressure.
• Suction superheat.
• Large clearance at the piston's top dead center.
• Insufficient cooling water supply to the cylinder head.

13. Excessively high suction superheat:

• Low refrigerant liquid volume in the evaporator, insufficient opening of the supply valve.
• Poor insulation or damage in the suction piping.
• Leakage or damage in the suction valve plate.

14. Excessively low discharge temperature:

• Wet compression stroke of the compressor.
• Excessive liquid supply in the intercooler.

15. Suction pressure of the compressor below normal evaporation pressure:

• Insufficient opening of the supply valve, insufficient liquid supply, and decreased evaporation pressure.
• Suction piping valve not fully opened.
• Valve core detached in the suction piping valve.
• Insufficient liquid ammonia in the system, pressure does not rise even with the supply valve fully open.
• Suction filter clogged.
• 'Liquid pocket' phenomenon in the suction piping.
• Excessively small diameter of the suction piping.

16. Violent pointer movement on the pressure gauge:

• Air present in the system.
• Loose pointer on the pressure gauge.
• Gauge valve opened too widely.

17. Compressor discharge pressure higher than condensation pressure:

• Discharge piping valve not fully opened.
• Partial blockage in the discharge piping.
• Unreasonable design of the discharge piping.

18. Knocking noise in the cylinder:

• Small clearance at the piston's top dead center.
• Large clearance between the piston pin and connecting rod small end hole.
• Loose fixing screws in the suction and discharge valve plates.
• Deformed or weakened spring in the dummy cap.
• Large clearance between the piston and cylinder.
• Excessive or dirty lubricating oil.
• Broken valve plate falling into the cylinder.
• Liquid slugging in the cylinder caused by refrigerant liquid entering.

19. Knocking noise in the crankcase:

• Large clearance between the connecting rod big end bushing and crankpin.
• Large clearance between the main bearing and main shaft journal.
• Broken cotter pin, loose connecting rod nut.

20. Cylinder wear:

• Improper clearance between the piston and cylinder, incorrect size of the piston ring groove.
• Impurities in the suction gas.
• Low viscosity or impurities in the lubricating oil.
• Excessively high discharge temperature, reducing oil viscosity.

21. Severe oil leakage from the shaft seal:

• Improper assembly.
• Wear on the friction surfaces of the rotating ring and fixed ring.
• Aged rubber sealing ring or inappropriate tightness.
• Weakened spring force in the shaft seal.
• Poor sealing between the back of the fixed ring and the shaft seal gland.
• Excessively high pressure in the crankcase.