Names of components of cold storage unit and fault maintenance methods

August 15, 2023



It is used to compress and drive the refrigerant in the refrigerant circuit. The compressor pumps the refrigerant from the low-pressure area, sends it to the high-pressure area for cooling and condensation after compression, and radiates heat into the air through the heat sink, and the refrigerant also changes from gas to liquid, and the pressure rises.



3. There is air in the refrigeration system:

Air in the refrigeration system will reduce the refrigeration efficiency, and the prominent phenomenon is that the suction and exhaust pressures increase (but the exhaust pressure has not exceeded the rated value), and the temperature from the compressor outlet to the condenser inlet increases obviously. Because there is air in the system, the exhaust pressure and temperature all increase. Elimination method: air can be released from the high-pressure cut-off valve several times in a row after a few minutes of shutdown, and some refrigerants can be properly filled according to the actual situation.



4. Low compressor efficiency: The low efficiency of refrigeration compressor means that the actual displacement decreases and the refrigeration capacity decreases accordingly under the same working condition. This phenomenon mostly occurs in compressors that have been used for a long time, and its wear is large, the fitting clearance of various parts is large, and the sealing performance of the valve decreases, resulting in a decrease in the actual displacement.

Exclusion method: 1. Check whether the paper pad of the cylinder head is leaked due to breakdown, and replace it if there is; 2. Check whether the high-pressure and low-pressure exhaust valves are not tightly closed, and replace them if any; 3. Check the fit clearance between piston and cylinder, and replace it if the clearance is too large.

5, evaporator surface frosting is too thick: The frost layer on the evaporator pipeline is getting thicker and thicker. When the whole pipeline is wrapped into a transparent ice layer, the heat transfer will be seriously affected, and the temperature in the warehouse will not fall within the required range. Elimination method: stop the machine to defrost, open the warehouse door to let the air circulate, or use a fan to speed up the circulation to reduce the defrosting time. Do not strike the frost layer with iron or wooden sticks to avoid damaging the evaporator pipeline.

6. There is refrigerant oil in the evaporator pipeline: In the process of refrigeration cycle, some refrigeration oil remains in the evaporator pipeline. After a long period of use, when there is more residual oil in the evaporator, it will seriously affect its heat transfer effect and cause poor refrigeration. Elimination method: remove the frozen oil in the evaporator. Disassemble the evaporator, blow clean it and then dry it. If it is not easy to disassemble, it can be blown out from the inlet of evaporator with compressor.

7, the refrigeration system is not smooth: Due to the uncleanness of the refrigeration system, after some time of use, dirt gradually accumulates in the filter, and some meshes are blocked, resulting in the decrease of refrigerant flow and affecting the refrigeration effect. In the system, the expansion valve and the filter screen at the suction port of the compressor are also slightly blocked. Elimination method: the micro-plugging parts can be removed, cleaned and dried before being installed.

8, refrigerant leakage: The compressor is easy to start (when the compressor parts are not damaged), the suction pressure is vacuum, the exhaust pressure is very low, the exhaust pipe is cold, and the water flow sound of the liquid cannot be heard in the evaporator. Elimination method: Check the whole machine, mainly the parts that are easy to leak. After the leakage part is found, it can be repaired according to the specific situation, and finally vacuumized and filled with refrigerant.

9, expansion valve hole frozen plug: (1) Improper drying treatment of main parts in refrigeration system; (2) The whole system is not completely evacuated; (3) The moisture content of the refrigerant exceeds the standard. Elimination method: connect a filter with moisture absorbent (silica gel, anhydrous calcium chloride) in series in the refriger10, expansion valve filter dirty plug: When there is a lot of coarse powdery dirt in the system, the whole filter screen will be blocked, and the refrigerant cannot pass through, resulting in no refrigeration. Elimination method: Remove the filter, clean it, dry it, and reload it into the system.ation system, filter out the moisture in the system, and then remove the filter.

10, expansion valve filter dirty plug: When there is a lot of coarse powdery dirt in the system, the whole filter screen will be blocked, and the refrigerant cannot pass through, resulting in no refrigeration. Elimination method: Remove the filter, clean it, dry it, and reload it into the system.


11, filter clogging: Desiccant is used for a long time and becomes paste to seal the filter or dirt gradually accumulates in the filter to cause blockage. Elimination method: remove the filter, clean and dry it, replace the washed desiccant and put it into the system.


12. Refrigerant leakage in the expansion valve bulb:

After the temperature sensing agent in the expansion valve temperature sensing package leaks, two forces below the diaphragm push the diaphragm to move upward, which is that the valve hole is closed and the refrigerant in the system cannot pass through, resulting in no refrigeration. At this time, the expansion valve does not frost, the low pressure is vacuum, and the air flow sound cannot be heard in the evaporator. Troubleshooting: shut down the stop valve, remove the expansion valve to see if the filter screen is blocked. If not, blow the inlet of the expansion valve with your mouth to see if it is ventilated. It can also be inspected visually or disassembled, and replaced when damaged.


13, there is residual air in the system: If there is air circulation in the system, the exhaust pressure will be too high, the exhaust temperature will be high, the exhaust pipe will be hot, the refrigeration effect will be poor, the compressor will run soon, and the exhaust pressure will exceed the normal value, forcing the pressure relay to act. Troubleshooting: Stop the machine and let air out of the exhaust valve hole.

14. Shutdown caused by low suction pressure: When the suction pressure in the system is lower than the setting value of the pressure relay, it will get an electric shock and cut off the power supply. Troubleshooting: 1. Refrigerant leakage. 2. The system is blocked.

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