What Are the Causes of Scroll Compressor Damage?

A scroll compressor is a positive - displacement compressor. Its compression components consist of a moving scroll and a stationary scroll. Its working principle is to utilize the relative revolution of the moving and stationary scrolls to form a continuous change in the enclosed volume, achieving the purpose of compressing gas. It is mainly used in air conditioners, refrigeration, general gas compression, as well as in applications such as automotive engine superchargers and vacuum pumps, and can replace traditional medium - and small - sized reciprocating compressors in a wide range.

The core issues of compressor operation - refrigeration oil and refrigerant:
Refrigeration oil: It has the functions of lubrication and sealing. Lack of oil or oil deterioration will lead to wear and high temperatures, which in turn will cause an increase in motor load, cylinder seizure, shaft seizure, etc.
Refrigerant: It is the working medium for cold quantity transfer and also plays a cooling role. Lack of refrigerant will lead to insufficient motor cooling and cause high temperatures. The oil may deteriorate at high temperatures, leading to wear. Refrigerant liquid slugging may cause the scroll to break.

Reasons for compressor damage and prevention methods
I. Lack of oil and insufficient lubrication
Manifested fault phenomena:
Internal protection of the compressor;
Exhaust or top temperature protection;
Over - current protection;
Power supply circuit breaker trips;
Abnormal operation sound of the compressor;
Excessively high temperature in the compressor cavity;
Analysis of fault causes:
Frequent start - stop of the compressor: When static, the oil and refrigerant accumulate in the compressor cavity. When starting, the oil is discharged from the compressor together with the refrigerant. If it stops running after a short time, the oil cannot return to the compressor in time. Repeating this process, the compressor will eventually burn out due to lack of oil.
Air or moisture in the system: When the compressor operates under high temperature and high pressure for a long time, the lubricating oil begins to acidify and thermally decompose, eventually turning into a gel - like substance, causing the compressor to seize.
System liquid return or refrigerant migration: It may dilute the lubricating oil, which is not conducive to the formation of an oil film, resulting in insufficient lubrication.
System refrigerant leakage: It may cause the leakage of lubricating oil, resulting in less lubricating oil in the compressor. The compressor rotates in reverse (such as wrong phase sequence): This makes it impossible to establish the internal pressure difference of the compressor, resulting in the inability to deliver lubricating oil to each friction surface.
Impurities entering the system: Impurities entering moving parts such as the scroll and crankshaft sleeve will cause wear. High temperatures may be caused, leading to oil deterioration. The decline in lubrication effect will cause the wear to deteriorate continuously, and eventually the compressor will burn out.

II. Compressor liquid slugging
Manifested fault phenomena:
The scroll breaks, and the fragments scratch the insulation layer of the motor coil. Current protection or internal protection of the compressor may occur;
The compressor can operate, but there is no temperature difference between the exhaust and return air and no high - low pressure difference, and the current is small;
The operation sound of the compressor is abnormal, or the compressor shaft is stuck. Current protection or circuit breaker trips as soon as it starts.
Analysis of fault causes:
Incomplete refrigerant evaporation: Common reasons include non - rotation of the indoor unit fan, small air volume, blocked air duct, dirty filter or heat exchanger, etc.
Non - unified power supply: The electronic expansion valve of the indoor unit that suddenly loses power still maintains a certain opening, but the fan does not operate. A large amount of refrigerant returns to the compressor directly without evaporation.

▲ Liquid slugging is extremely destructive. The scroll will be broken in a short time, the compression chamber will be damaged, and at the same time, the fragments may scratch the insulation layer of the motor, leading to a short - circuit.
Excessive refrigerant addition: This leads to a large amount of liquid return in the system (it is more likely to occur in low - temperature environments with small - load refrigeration and low - temperature heating).
Excessive oil addition: This leads to oil slugging in the system (rarely occurs). For high - pressure - chamber compressors, too much lubricating oil will increase the resistance of motor rotation, increase the input power, and deteriorate the motor heat dissipation, affecting the motor life.

III. Compressor burnout due to high temperature
Manifested fault phenomena:
Exhaust or top temperature is too high;
The temperature in the compressor cavity is too high;
High - pressure protection (when the system is blocked);
Current protection or circuit breaker trips.
Analysis of fault causes:
Too little refrigerant addition or refrigerant leakage: This leads to too high exhaust and return air temperatures.
Problems with refrigeration oil: Refrigeration oil leakage or problems with the quality of refrigeration oil.
▲ High temperature causes the carbonization of compressor oil, aggravating wear.
System dirt blockage or ice blockage (ice blockage mainly refers to the return air pipe): This leads to too high exhaust or top temperature.
Insufficient system vacuum: The compressor compresses air, resulting in a large compression ratio and high temperature.
▲ High temperature causes the oil to carbonize, and the scroll wears and turns black.

Harsh system operating environment: Blocked air ducts, poor return air, dirty heat exchangers, etc., cause high condensing pressure and a continuous rise in exhaust temperature.
Too long connecting pipes or use of small - diameter pipes: The system resistance increases, leading to an increase in exhaust temperature and pressure.

IV. Analysis of reasons for compressor burnout
Manifested fault phenomena:
Short - circuit and open - circuit;
Frequent contactor suction/burnout;
Over - current protection;
Internal protection of the compressor, power switch trips;
Excessively high temperature in the compressor cavity. After the motor burns out, some phenomena or direct causes that led to the burnout are covered up, making post - event analysis and cause investigation more difficult.
Analysis of fault causes:
Abnormal wear of the compressor caused by various reasons: All may cause the worn metal chips to damage the insulation layer of the coil and burn out the motor.
▲ Due to abnormal wear of the compressor, impurities are generated. Sharp impurities may scratch the insulation layer of the motor winding, or metal chips adhere to the insulation layer, causing the motor to short - circuit or open - circuit.
Melting or abnormality of the contactor contacts: Such as phase - loss and phase - deviation will directly affect the compressor motor.
Power supply phase - loss or voltage abnormality: The variation range of the power supply voltage should not exceed ± 10% of the rated voltage, and the voltage unbalance rate between three phases (380V) should not exceed 3%. When the voltage is unbalanced, the load current is 4 - 10 times that of normal operation.
Insufficient motor cooling: When there is a large amount of refrigerant leakage or the evaporation pressure is too low, the mass flow rate of the system will decrease, making it impossible for the motor to be cooled well.

The motor will experience frequent protection after overheating.

IV. Avoid compressor burnout from the source
Do a good job in dust - proof and waterproof treatment of copper pipes before installation: Avoid impurities and moisture from entering the refrigerant pipeline and compressor.
Use special tools (pipe cutters) to cut copper pipes: Avoid copper chips generated when cutting copper pipes with a hacksaw or other tools from entering the pipeline.
Use nitrogen protection during pipeline welding: Avoid welding slag and scale from entering the refrigerant pipeline.
Unify the power supply of indoor units in the same system: Avoid refrigerant liquid slugging caused by some indoor units directly losing power.
The indoor units of multi - connected air - conditioners should not be used as computer room air - conditioners: Avoid the outdoor unit running at a low load for a long time or starting and stopping frequently, which may lead to lack of oil in the compressor.
The size of the air - outlet grille of the indoor unit should be matched, and the filter should be cleaned regularly: Avoid air outlet obstruction due to a small grille size or misaligned installation, or a decrease in air volume due to a dirty filter, resulting in incomplete refrigerant evaporation.
Calculate the refrigerant addition amount according to the standard and use an electronic scale for addition: Avoid liquid slugging or too high refrigerant temperature caused by too much or too little refrigerant.
Pay attention to the power supply voltage of the air - conditioning system and standardize the power supply wiring: Avoid large - current in the compressor caused by unstable power supply voltage, unbalanced three - phase voltage, phase - loss, etc.
Pay attention to the horizontal placement of the branch pipes for parallel outdoor units: Avoid uneven distribution of refrigerant and oil between outdoor unit modules, resulting in some outdoor units having too much or too little refrigerant/oil.