Common Faults and Solutions of Scroll Compressors in Refrigeration and Freezing Systems

In the long-term operation of refrigeration and freezing systems, the scroll compressor, as a core component, inevitably encounters various faults. Understanding common fault phenomena, causes, and corresponding solutions is key to ensuring stable system operation and extending equipment service life. The following will provide a detailed analysis of possible problems and handling methods of scroll compressors in practical applications.
 

1. Poor Refrigeration Performance

Fault Phenomenon: The temperature of the refrigeration and freezing equipment cannot reach the set value, or the cooling speed is significantly slowed down, the equipment running time is extended, and energy consumption increases.

Possible Causes and Solutions:

Refrigerant Leakage: Aging or damage to the sealing parts of the scroll compressor (such as shaft seals, connection pipe interfaces) can cause refrigerant leakage. Leak points can be detected by pressure testing or applying soapy water. Once leakage is found, recover the remaining refrigerant first, replace damaged seals, re-weld or tighten pipe connections, and finally charge the appropriate amount of the same model refrigerant according to regulations.

Improper Refrigerant Charging: Both insufficient and excessive charging affect refrigeration performance. When undercharged, both suction and discharge pressures are low; overcharging causes suction and discharge pressures to be too high. Use professional tools to detect system pressure and temperature, and precisely adjust refrigerant charge according to the parameters in the equipment manual.

Severe Frost on Evaporator: During long-term operation, moisture in the air condenses and forms frost on the evaporator surface. Excessive frost hinders heat exchange and reduces the evaporator's heat absorption efficiency. Regular defrosting of the evaporator is necessary, which can be done by natural defrost during shutdown, electric defrost, or hot gas defrost. Also, check whether the defrosting device is functioning properly.

Poor Condenser Heat Dissipation: Dust and debris accumulation on the condenser surface or poor ventilation affect its heat dissipation ability, causing increased compressor discharge pressure and reduced refrigeration efficiency. Regularly clean the condenser surface, ensure good ventilation around it, check if the fan operates normally, and repair or replace it promptly if faulty.
 

2. Abnormal Compressor Vibration or Noise

Fault Phenomenon: The compressor vibrates violently during operation, accompanied by abnormal friction sounds, impact noises, or piercing noise, which may cause equipment parts to loosen severely.

Possible Causes and Solutions:

Improper Installation: If the compressor foundation is not solid, the level is off, or there is stress when connected to pipes, vibration and noise may occur. Recheck the compressor installation foundation to ensure it is level and stable, adjust pipe connections to avoid extra pulling or pressure on the compressor.

Internal Part Wear: After long-term use, key parts such as the scroll plate and bearings may wear, increasing clearance and causing vibration and noise during operation. Disassemble the compressor, inspect wear, replace severely worn parts, and perform precision inspection and adjustment on related components.

Liquid Hammer Phenomenon: Liquid refrigerant entering the compressor cannot be compressed during compression, causing strong liquid hammer noise and vibration. This may be due to an overly open expansion valve or poor evaporator gas return. Adjust the expansion valve opening to ensure full evaporation of refrigerant in the evaporator; check and clear any blockages in the evaporator and gas return pipes.

Compressor Oil Shortage: Insufficient lubrication oil or degraded oil quality increases friction between parts, causing abnormal noise and vibration. Regularly check the compressor's oil level and quality, replenish or replace with qualified lubricating oil timely, and ensure the oil circuit is unobstructed for normal oil circulation.
 

3. Compressor Does Not Start

Fault Phenomenon: After power is turned on, the compressor does not respond or operate, and the equipment cannot refrigerate.

Possible Causes and Solutions:

Electrical Faults: Loose or broken power lines, or damage to electrical components such as the compressor's start capacitor, contactor, or relay, can prevent the compressor from powering on. Check if power connections are secure, use a multimeter to test electrical components for continuity and performance, and replace damaged parts. Also, check if the control circuit and protection devices (such as overheat or overload protection) are functioning properly; reset protection devices after troubleshooting.

Compressor Seizure or Shaft Lock: Due to poor lubrication or mechanical debris, moving parts inside the compressor may seize or lock. For minor seizure, try tapping or capacitor start methods to repair; for severe seizure or locking, disassemble the compressor, clean internal debris, repair or replace damaged parts, reassemble, and ensure proper fit of all components.

Abnormal System Pressure: Excessively high or low system pressure triggers compressor protection mechanisms, preventing startup. Check system pressure; if too high, it may be caused by poor condenser heat dissipation or overcharging of refrigerant, requiring targeted solutions; if too low, it may be due to refrigerant leakage or pipe blockage, requiring leak detection, pipe clearing, and refrigerant replenishment.
 

4. Frequent Compressor Start-Stop

Fault Phenomenon: The compressor frequently starts and stops within a short time, significantly shortening the operating cycle and affecting equipment service life.

Possible Causes and Solutions:

Temperature Controller Fault: Improper temperature controller settings, inaccurate sensor probe position, or controller damage can cause frequent compressor start-stop. Re-adjust the temperature controller settings to match actual equipment needs; check if the sensor probe is installed properly and can accurately sense temperature changes; replace the controller promptly if damaged.

Large System Pressure Fluctuations: Blockages, valve faults, or poor refrigerant circulation in the refrigeration system cause pressure fluctuations. Check if expansion valves, dryers, solenoid valves, and other components work properly; clear blocked pipes; repair or replace faulty valves to ensure smooth refrigerant circulation and stable system pressure.

Unstable Power Supply Voltage: Voltage that is too low or too high affects normal compressor startup and operation, causing frequent start-stop. Use a voltmeter to check if the supply voltage is within the compressor's rated range; if unstable, install a voltage stabilizer; also check for poor contact in power lines and repair promptly.

The causes of failures in scroll compressors within refrigeration and cold storage systems are complex and diverse. During daily use, equipment maintenance should be strengthened, with regular checks of various parameters and component conditions to promptly identify and resolve potential issues. When a failure occurs, it is necessary to accurately determine the cause and adopt scientific and reasonable solutions to ensure the continuous and stable operation of the scroll compressor and the refrigeration and cold storage system.