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Inspection method for common faults of commercial supermarket freezers

Update:20-06-2022
Summary:

The fault judgment of commercial supermarket freezers i […]

The fault judgment of commercial supermarket freezers is an important link in the maintenance of supermarket freezers. Generally, the method of "seeing, touching, listening, and testing" is often used to judge the faulty part.

Under normal working conditions, the frosting on the surface of the evaporator should be uniform. Therefore, when judging the failure of the supermarket freezer, you should first check the frosting of the evaporator.

Under normal working conditions, the frosting on the surface of the evaporator should be uniform. Therefore, when judging the failure of the supermarket freezer, you should first check the frosting of the evaporator.

(1) The surface of the evaporator of the normal working direct cooling supermarket freezer should have frost and the frost layer should be uniform and thick. The phenomenon indicates that the refrigeration system of the supermarket freezer is not working properly. If periodic frosting occurs, the refrigeration system contains moisture and ice blockage may occur. If the evaporator is still not frosted after working for a long time, it means that there may be a leak in the refrigeration system.

(2) Observe whether there is frost or condensation on the capillary and drying filter. If there is, it indicates that there is a local blockage. Observe whether there is frost in the suction pipe of the compressor and whether there is condensation in the filter of the box door, which can determine whether the refrigerant is excessive and whether the anti-condensation pipe is faulty. Then observe the refrigeration pipeline system, mainly to observe whether there are oil traces at the joints of the pipeline. If there are oil traces on the outside of the pipe, it means that there is leakage of the refrigerant here. Since the refrigerant has a strong penetrating force and can be mutually dissolved with the refrigeration oil in any proportion, if there is oil traces, it means that there is leakage of the refrigerant. .

Listen to the operation of the supermarket freezer. When the supermarket freezer is working normally, the compressor will emit a faint sound, which is the high-pressure liquid refrigerant entering the low-pressure evaporator through the capillary tube, and the evaporator absorbs heat and cools. Open the door of the box, put your ears on the outside of the evaporator or the box, you can hear the sound of airflow, which means that the supermarket freezer is working normally. The following sounds are abnormal.

(1) After the power is turned on, you hear a "humming" sound, indicating that the motor has not started, and the power supply of the supermarket freezer should be cut off immediately.

(2) Hear the sound of "hissing" airflow in the compressor casing, which is the sound of high-pressure gas breaking into the casing after the high-pressure buffer tube in the compressor is broken.

(3) If the supermarket freezer compressor makes an abnormal sound of "dangdang" during operation, it means that the hanging spring in the compressor shell is loose or broken, and the impact sound after the compressor is tilted.

(4) If you hear a "click" sound, it is the impact sound of the metal inside the compressor, and the moving parts inside the surface collide due to loosening.

(5) If the sound of airflow in the evaporator cannot be heard, it means that the refrigeration system is dirty and blocked. Ice or oil blockage. If the sound of airflow is very small, it means that the refrigerant in the supermarket freezer has basically been leaked.

Touch the relevant parts by hand to feel their temperature, and analyze and judge the fault location.

(1) When the room is 300C-, after touching the power supply of the supermarket freezer for 30 minutes, the exhaust pipe should be hot when you touch it. It should feel warmer to the touch in winter.

(2) Check whether the surface temperature of the condenser is normal by hand. When the supermarket upright freezer works normally and continuously, the surface temperature of the condenser is about 55°C, the upper part is the hottest, the middle part is hotter, and the lower part is slightly hotter. The temperature of the condenser is related to the ambient temperature. The temperature in winter is about 55 ℃, the upper part is the hottest, the middle part is hotter, and the lower part is slightly hotter. Condenser: The temperature is related to the ambient temperature. In winter, the temperature is lower, and the condenser temperature is lower; in summer, the temperature is higher, and the temperature is higher.

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