Five common problems of refrigeration system
First, Treatment of insufficient refrigerant
1. Failure phenomenon: The cooling effect of the whole machine is poor, the water outlet is only a little cold, and the pressure on the high-pressure side and the low-pressure side is found to be low with the manifold pressure gauge (under the normal speed of the compressor, when the ambient temperature is about 35 ℃, the low pressure The meter index is lower than 1kg / cm2, the high-pressure meter index is lower than 10kg / cm2), and the bubble flow can be seen from the sight glass.
2. The cause of the failure: the refrigeration system has a refrigerant leakage point, which results in insufficient refrigerant.
3. Treatment method: 1). Use electronic leak detector to find the leak point and repair or replace parts.
2). If the parts are not replaced, only the appropriate amount of refrigerant can be added; if the parts are replaced, the appropriate amount of refrigeration oil should be added as required, and the refrigerant should be added after the system is evacuated.
Second, Overcharge of refrigerant
1. Failure phenomenon:
The cooling effect is poor, and the pressure on the high-pressure side and the low-pressure side is too high when checked with a manifold pressure gauge (when the compressor speed is normal and the ambient temperature is 35 ° C, the high-pressure gauge pressure is about 19 kg / cm2, and the low-pressure gauge pressure is 2.3 kg / cm2, and no air bubbles can be seen in the sight glass.
2. Failure reason: Too much refrigerant is added in the refrigeration system, so that the refrigeration capacity cannot be fully exerted, resulting in poor refrigeration effect.
3. Treatment method: Connect the manifold pressure gauge to the system, and slowly loosen the manual valve on the low pressure side of the manifold pressure gauge, so that the refrigerant is slowly discharged (cannot be discharged from the high pressure side, because the refrigerant will be taken out from the high pressure side) A large amount of freezing oil) until the pressure on the high and low sides is normal, and the refrigerant flows clearly from the sight glass, and occasionally bubbles flow through.
Third, the cooling system is mixed with air
1. Failure phenomenon: the cooling capacity of the whole machine is reduced; the pressure on the high pressure side is found to be high when the manifold pressure gauge is checked, and the pressure on the low pressure side may sometimes be higher than the normal value (the compressor speed is normal and the ambient temperature is 35 ° C At this time, the pressure on the high-pressure side is higher than 20kg / cm2; and the pointer of the high-pressure meter is oscillating; on the other hand, many bubbles can be seen flowing from the sight glass.
2. Reasons for failure:
Air is mixed in the system. Mainly after the assembly or overhaul, the vacuum is not thorough; when charging the refrigerant or adding refrigeration oil, the air is brought into the system, or when the system is working under negative pressure, the air is mixed through the tight places. After the refrigerant enters the air, it has a certain pressure, and the refrigerant also has a certain pressure. In a closed container, the total gas pressure is equal to the sum of the partial pressures, so the high and low pressure gauge readings are higher than normal.
3. Treatment method: 1) Release refrigerant (release slowly from low pressure side with pressure gauge). 2) Check the cleanliness of the compressor oil. 3) Refill the refrigerant after vacuuming.
Fourth, "ice blockage" appears in the refrigeration system
1. Failure phenomenon: The refrigeration system periodically cools suddenly but not suddenly. During operation, the pointer on the low pressure side of the manifold pressure gauge often fluctuates between the negative pressure and the normal value.
2. Cause of failure: Moisture is mixed into the refrigerant in the refrigeration system. Because the water is incompatible with the refrigerant, when the refrigerant flows through the orifice of the expansion valve, the temperature drops suddenly. These are mixed in the refrigerant The water will easily form small particles of ice in the vicinity of the small hole of the throttle valve or around the valve pin hole, which is spherical or hemispherical. When the ice particles are condensed to a certain extent, the throttle channel is blocked and an ice jam fault is formed. . When ice blocking occurs due to icing, the refrigeration system cannot work properly, and the refrigeration effect is significantly reduced, even without refrigeration.
At this time, the low pressure gauge appeared negative pressure, so the temperature of the ice block was obviously raised, the ice particles of the ice block melted into water, so that the ice block phenomenon disappeared, the refrigeration system resumed normal operation, the refrigeration was good, and the low pressure side pressure returned to normal. After a while, there was ice blockage in the system and the system was not working properly.
3. Treatment method: 1) Because the desiccant is in supersaturated state, it is necessary to replace the reservoir with desiccant and add 30ml of freezing oil. 2) Vacuum the system and add a specified amount of refrigerant.
Fifth, dirty blockage troubleshooting
1. Failure phenomenon: poor cooling effect or no cooling. When the air conditioning system is running, the readings of the high and low pressure gauges on the manifold pressure gauge are less than the normal value. (When the compressor speed is normal and the ambient temperature is around 35 ° C, the pressure on the high pressure gauge side is less than 9 kg / cm2, and the pressure on the low pressure side is Negative pressure), and there is frost or dew on the filter and capillary tube.
2. The cause of the failure: the dust in the refrigeration system adheres or adheres to the filter screen at the inlet end of the filter, or the interface between the capillary and the filter screen, so that a local throttling phenomenon is formed at this location, and the temperature drops rapidly, and condensation or condensation occurs Frost.
3. Treatment method: If there is frosting at the filter inlet, and the sound of intermittent airflow is heard, tap the filter body with a small wrench, the airflow sound changes, and the frost layer of the filter and capillary melts at the same time, which can be judged The filter inlet filter is clogged.
At this time: ① Remove the capillary, clean the filter and blow dry, and reinstall it. Or replace the filter ② evacuate and fill the refrigerant to the specified amount.