Installing, maintaining, and debugging refrigeration equipment, these 10 common faults are common

January 30, 2024

  Installing, maintaining, and debugging refrigeration equipment, these 10 common faults are common


1.The exhaust temperature of the refrigeration system is too low:

The low exhaust pressure is mainly due to the small or even stopped flow of refrigerant in the refrigeration system pipeline. Although its phenomenon is manifested at the high voltage end, the reasons are mostly generated at the low voltage end.

Possible reasons include:

The expansion valve hole is blocked, causing a decrease or even cessation of liquid supply;
Ice or dirt blockage of the expansion valve, as well as filter blockage;

2.Refrigeration system return liquid:

For small refrigeration systems using capillaries, adding too much liquid can cause liquid return. In addition, when the evaporator frosts severely or the fan malfunctions, the heat transfer deteriorates, and the unexpired liquid can cause liquid return. Frequent temperature fluctuations can also cause the expansion valve to malfunction and cause liquid return.

For refrigeration systems that use expansion valves, the selection and improper use of return liquid and expansion valves are closely related. Excessive selection of expansion valve, too low setting of superheat, incorrect installation method of temperature sensing package, damaged insulation wrapping, and failure of expansion valve may all cause liquid return.

For refrigeration systems that are difficult to avoid liquid return, installing a gas-liquid separator can effectively prevent or reduce the harm of liquid return.


3.The suction temperature of the refrigeration system is high:

Other reasons such as poor insulation of the return air pipeline or excessively long pipeline can cause high suction temperature. Insufficient refrigerant charge in the system or too small opening of the expansion valve can also cause high suction temperature. In addition, clogging of the expansion valve filter and insufficient liquid supply in the evaporator may also cause an increase in suction temperature.

4.Liquid hammer:

To prevent liquid hammer, it is necessary to avoid suction temperatures that are too high or too low. If the suction temperature is too low, it indicates that the refrigerant is not completely evaporated in the evaporator, which will reduce the heat transfer efficiency of the evaporator. The suction of wet steam will also form a compressor liquid hammer. To prevent liquid hammer, it is required that the suction temperature be slightly higher than the evaporation temperature, that is, there should be a certain degree of superheat.

5.Starting the refrigeration system with liquid:

The bubbling phenomenon during liquid start can be observed on the oil level mirror. The root cause is that a large amount of refrigerant dissolved in the lubricating oil and settled under the lubricating oil suddenly boils when the pressure suddenly decreases, causing foaming of the lubricating oil and easily causing liquid hammer. To prevent this situation, some measures can be taken, such as installing a crankcase heater (electric heater) and installing a gas-liquid separator on the return air pipeline.


6.Oil return problem in the refrigeration system:

Lack of oil can cause serious lubrication problems. Installing an oil separator can quickly return oil and prolong the operation time of the compressor without oil return. When the compressor is higher than the evaporator, there is no oil return bend on the vertical return pipe. Corresponding measures should be taken to improve the oil return problem, such as increasing the number of oil return bends. Frequent starting of the compressor is not conducive to oil return, and the number of starts should be minimized as much as possible.


7.Low evaporation temperature of refrigeration system:

The evaporation temperature has a significant impact on refrigeration efficiency. Although reducing the evaporation temperature can reduce the temperature difference, the refrigeration capacity of the compressor will decrease and the power consumption will increase. Therefore, the evaporation temperature should be appropriately increased to improve refrigeration efficiency. At the same time, attention should be paid to factors such as condensation pressure and load.

8.Refrigeration system exhaust overheating:

The main reasons for exhaust overheating include: high return air temperature, motor heating, high compression ratio, counter expansion and gas mixing, compression temperature rise and refrigerant type, and high condensation pressure. The specific reason can be found in relevant materials or professional books.

9.Low suction temperature of refrigeration system:

Excessive opening of the expansion valve or excessive refrigerant charging may cause the suction temperature to be too low. The opening degree of the expansion valve should be adjusted to ensure that the temperature measured by the temperature sensing element is accurate to avoid such problems.

10.Fluorine deficiency in refrigeration system:

When the refrigeration system lacks fluorine, certain specific phenomena may occur. Firstly, the regulating pressure of the expansion valve may decrease or be partially blocked, at which point the valve cover (bellows) and even the inlet of the expansion valve may frost. If there is too little or almost no fluorine, the surface of the expansion valve may not have a significant reaction, and only a slight airflow sound can be heard.
In addition, observing the frozen area is also a basis for judgment. If icing starts from the separation head, it is likely due to fluoride deficiency; If icing starts from the compressor return pipe, it may be due to excessive fluoride.
It should be noted that fluorine is an important component in refrigeration systems, and a lack of fluorine may lead to a decrease in refrigeration efficiency, affecting the normal operation of the system. Therefore, if a lack of fluoride is found, an appropriate amount of fluoride should be replenished in a timely manner to ensure the normal operation of the system.


Shanghai KUB Refrigeration Equipment Co., Ltd.
Address : No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai
Factory Address : No. 328 on the 4th plant hengyong Road, Jiading District, Shanghai
Work Time : 8:30-17:30(Beijing time)
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