Some Reasons For Compressor Failures

Compressor failure problem is basically caused by these reasons: liquid compression; freon-deficient operation; poor oil return; vacuum operation; poor system cleanliness. It can be said that 90% of compressor failure caused by these reasons. Eurostars engineers focuses on these problems and share their analysis.

1.Liquid compression

(1)Phenomenon analysis:

The liquid refrigerant enters the compressor to produce liquid compression, which causes the scroll of the moving and fixing plates to break. When the liquid refrigerant enters the compressor cavity, the scroll is subjected to extreme transverse shearing force due to the incompressibility of the liquid, which causes the scroll of the moving and fixing plates to break and makes the compressor jam. In addition, the broken pieces fall on the motor and will cause the motor short-circuited and burned.

(2)Reasons for liquid compression: 

The evaporator fan does not rotate or the pipeline is blocked.

Too much refrigerant is filled during maintenance or installation.

(3)Solutions:

Adjust the appropriate amount of refrigerant, to ensure that there is a heating belts at the bottom of the compressor and the power is normal. For long-term storage or working at low ambient temperature, the chiller must be preheated for 6 hours before starting it. After-sales installation personnel should emphasize it.

2.Freon-deficient operation

(1)Phenomenon analysis:

When the compressor is running short of freon, the center temperature of the moving and fixing plates will increase. When the temperature reaches a certain level, the end sealing ring will melt, and the melt will stick between the moving and fixing plates, which will increase the friction between them, and it will be stuck or broken when the situation is serious. At this time, the motor temperature will also rise and cause frequent IP actions, which will cause the protector to fail, and the motor will burn out. In addition, due to the carbonization of the O-ring, it will cause high and low pressure failures, the exhaust pressure becomes small when the compressor is powered on.

(2)Reason analysis:

There is a lack of freon or insufficient freon in the chiller system.

Poor installation, leakage at the welding joints. 

(3)Solutions:

Ensure enough volume of refrigerant in the chiller or air-conditioning system.

Check all pipe joints and welds whether leaks. 

A low-voltage protector must be added to the chiller system.

3.Poor oil return

(1)Phenomenon analysis:

The compressor is unable to deliver enough oil to the lubrication parts due to the lack of oil, which makes the friction of each lubrication part intensify friction from bottom to top (especially the uppermost moving plate bushing and crankshaft most serious, because its force is several times than other two lubrication parts underneath) , and causes the shaft sleeve of the moving plate heat up, and eventually burns the shaft sleeve, or even jammed . In this case, the increasing of motor temperature causes the protector to operate frequently and finally fail to protect. The continuous high current applied to the unprotected compressor will make the motor windings burnt.

(2)Reason analysis:

Compressor: the oil circuit is blocked, there is no oil absorption sheet, and the oil volume is insufficient when leaving the factory.

The chiller system: the capillary tube is blocked, the oil return in the liquid receiver is impervious, the size of the hole is not suitable, the inlet and outlet are connected reversely, etc.

Installation: there is no oil return bend in the pipeline, hard bends in the pipeline, impurity enters the pipeline when the pipeline penetrates the wall, or the pipeline is too long and the height difference is too high, and the appropriate amount of refrigerating oil and refrigerant is not added to the system.

Operating: the system lacks oil and frequent defrosts due to system leakage.

(3)Solutions:  

When installing, setting an oil return bend in the pipeline to improve the oil return environment.

In the case of a long pipeline or a large drop between the inside and outside of the machine, an appropriate amount of refrigerating machine oil and refrigerant should be added to the chiller or central air conditioning system.

4.Vacuum operation

(1)Phenomenon analysis:

When the compressor is running under vacuum, the temperature in the center of the moving and fixing plates will rise rapidly, and the sealing ring at the compressor will melt and cause the compressed gas to leak internally, resulting in low exhaust pressure. The scroll is heated and expanded, causing hard friction between the moving plate and the support surface, which may cause the compressor to jam in severe cases.

(2)Reason analysis:

The freon collection time is too long, causing the compressor to operate under the condition of less than 0Pa. Refer to the regulations of air conditioning industry, it is recommended to set the pressure value at 0.05Mpa when collecting freon, and when the pressure is lower than this, immediately stop collecting freon. 

It is forbidden to use the compressor as a vacuum pump during installation.

When installing and debugging, please check whether the shut-off valve is fully opened and whether there is enough refrigerant in the system.

5.Poor cleanliness

(1)Phenomenon analysis:

The refrigeration compressor has problems such as shaft holding, poor insulation, and copper crossing.

(2)Reason analysis:

When welding, pay special attention to the entry of debris, scale and moisture into the system, because these substances are prone to chemical reactions in contact with refrigerants or refrigerating oil, which will deteriorate the insulation of the compressor motor, the oil supply system of the compressor will cause the movable parts to stick, and result in shaft holding. Pay attention to pipeline maintenance during installation to prevent debris from entering the pipeline.

(3)Solutions:  

When welding piping, make sure to nitrogen flow with a purity of 99.8% or more. The flow rate of nitrogen is best to be felt by the skin (flowing nitrogen pressure is 0.02Mpa).

During the construction process, the ends of each pipe must be sealed.

During the pipeline welding process, the pipeline is purged in sections. (Use 0.5MPA nitrogen for purging) Standardize operations such as vacuuming and welding.